IELTS Real Reading Test 2025 - Q2 Test 3 with Practice Test, Answers And Explanation
Luyện tập đề IELTS Real Reading Test 2025 - Q2 Test 3 được lấy từ cuốn sách Real Test 2025 - Q2 với trải nghiệm thi IELTS trên máy và giải thích đáp án chi tiết bằng Linearthinking, kèm answer key và list từ vựng IELTS cần học trong bài đọc.
IELTS Real Reading Test 2025 - Q2 Test 3 with Practice Test, Answers And Explanation
Passage
❓ Câu hỏi passage 1
Question 1 - 6
Do the following statements agree with the information given in the Reading Passage?
TRUE if the statement agrees with the information
FALSE if the statement contradicts the information
NOT GIVEN if it is impossible to say what the writer thinks about this
1
During his 2007 dive, Michiels expected to encounter total darkness at about 15 metres.
2
Michiels could see the red markings on fish without the aid of the red filter.
3
Other divers had assumed they would see fish with red markings.
4
All the fish with red markings that Michiels found during his diving expeditions came from the Red Sea.
5
Michiels first thought of the possibility that fish could fluoresce while he was in Germany.
6
Michiels remains uncertain as to what creates fluorescence in fish.
Question 7 - 13
Complete the notes below.
Choose ONE WORD ONLY from the passage for each answer.
Michiels's findings
Michiels has observed:
- 50 types of fish with red fluorescence in total
- markings mainly near the
7.
Some of Michiels's beliefs are that:
- red fluorescence is used specifically for
8.
purposes
- fish, like some animals, use fluorescence to keep
9.
away
- gobies depend on red fluorescence to show their
10.
- there are variations in the markings of fish among those
11.
which are very similar
Other benefits of red fluorescence:
- fish cannot easily be seen near backgrounds of
12.
which give off a red light
- helps some fish catch their prey
The ability to see red amongst fish:
- the only fish proven to have this ability is the
13.
Passage
❓ Câu hỏi passage 2
Question 14 - 19
The Reading Passage has six paragraphs A-F.
From the list of headings below choose the most suitable heading for each paragraph.
Write the appropriate numbers i-x
List of Headings
I
Robots on Earth – a re-evaluation
II
The barriers to cooperation in space exploration
III
Some limitations of robots in space
IV
Reduced expectations for space exploration
V
A general reconsideration of human/robot responsibilities in space
VI
Problems in using humans for space exploration
VII
The danger to humans of intelligent machines
VIII
Space settlement and the development of greater self-awareness
IX
Possible examples of cooperation in space
14
Paragraph A
15
Paragraph B
16
Paragraph C
17
Paragraph D
18
Paragraph E
19
Paragraph F
Question 20 - 21
Choose TWO letters, A-E
According to the writer, which TWO predictions about artificial intelligence have not yet been fulfilled?
A
Robots will work independently of humans.
B
Robots will begin to oppose human interests.
C
Robots will be used to help humans perform tasks more efficiently.
D
Robots will think in the same way as humans.
E
Robots will become too costly to use on space missions.
Question 22 - 26
Complete the summary below.
Write ONE WORD ONLY from the passage for each answer.
<b>Humans in space - the Mars Outposts approach and its implications</b>
One way of exploring space would be through collaboration between humans and robots. For example, when exploring the planet Mars, robots could be used to set up and do initial research before humans arrive. In other cases, humans could stay in orbiting and give orders to robots working on the surface of the planet.
This would increase the speed of with the robots. In such ways, robots might be used to work in space in commercial enterprises or . However, the final aim of humankind may be the of space and this could in turn change people's attitudes towards Earth.
Passage
❓ Câu hỏi passage 3
Question 27 - 31
Choose the correct letter, A, B, C or D.
Write the correct letter in boxes on your answer sheet.
27
The optimum amount of fluorine in fluoridated water is calculated partly according to
A
how hot the area is.
B
how warm the water is.
C
how many dental problems there are in the community.
D
how much fluorine the community chooses to have in its water.
28
One reason given by the writer for opposing fluoridation is that
A
it may contribute to tooth decay
B
it will be unacceptably expensive for the public.
C
obligatory fluoridation takes away personal freedom.
D
excessive fluoride could be added to the water by mistake.
29
The writer mentions Kuhn in order to
A
provide a contrast with the view of Collins.
B
support the rational nature of scientific inquiry.
C
demonstrate that Kuhn did not argue his case adequately.
D
show that science can be influenced by non-scientific considerations
30
What did Sutton’s research discover about earlier studies in North America?
A
There were failings in the way they were carried out.
B
The scientists involved had achieved unique results.
C
Proponents of fluoridation had not understood its long-term effects.
D
Fluoridation had a greater effect on tooth decay than previously believed.
31
In the last paragraph, what does the writer say about scientists?
A
They should reveal their true motivations.
B
They should not decide the fluoridation policy.
C
They are solely concerned with scientific truths.
D
They cannot reach agreement on the fluoridation issue.
Question 32 - 35
Do the following statements agree with the information given in Reading Passage?
In following statements below, choose
YES if the statement agrees with the information
NO if the statement contradicts the information
NOT GIVEN if it is impossible to say what the writer thinks about this
32
Scientific knowledge should be kept separate from social values.
33
Many sociologists have disregarded the doubts that some scientists have concerning fluoridation.
34
Sutton's findings have been given insufficient attention by scientists outside of North America.
35
There are valid arguments on both sides of the fluoridation debate.
Question 36 - 40
Complete each of the following statements with the best ending A-G from the box below.
List of Endings
A
the results of scientific research are not always understood at first.
B
science is an unbiased discipline.
C
people should be able to choose whether they want fluoride.
D
there is insufficient proof to support a cautious approach.
E
the serious damage fluoride causes far outweighs any positive effects.
F
children are not the only ones who benefit from fluoridation.
G
scientific knowledge is affected by the beliefs of everyone concerned.
The traditional view of science is that
36
A sociological view of science argues that
37
Collins is of the opinion that
38
The writer suggests that a supporter of fluoridation may conclude that
39
The writer suggests that an opponent of fluoridation may conclude that
40
DOL IELTS Đình Lực
05/05/2026
📖 Bài đọc passage 1
Deep sea discovery
Recent research has provided new insights into how fish communicate
A
A.
Nico Michiels is an ecologist from the University of Tubingen in Germany who spends part of each year in Egypt, where he dives in the Red Sea, observing fish life and gathering data on its coral reefs. In September 2007 he decided to find out how far red light could penetrate the ocean depths. Seawater absorbs different colours at different depths, and as an experienced diver, Michiels was aware that red light is extinguished not far below the surface whereas blue-green light penetrates deeper. To find out the depth at which red disappeared in this particular ocean, however, he attached a special plastic filter to his dive mask which was designed to block out all colours except red. Then he began to descend. In theory, once he reached about 15 metres, he should have been plunged into darkness. Instead, something totally unexpected happened. Sure enough, 20 metres down it was as dark as night. 'All the fish disappeared. With no light from the surface, they were effectively black and had become invisible,' he says. 'But it didn't stay black for long. Then I saw a group of goby fish with bright red eyes lit up against the background. After that red spots began to show up all over the reef.'
B
B. Even with the red filter removed, Michiels could pick them out without much trouble once his eyes grew accustomed to the gloom. It seems strange that no diver or researcher had spotted all this red before, but as Michiels points out, no one saw it because no one expected to see it. On that one dive Michiels discovered three fish species with prominent red markings, and has found many others since.
C
But how can fish appear red where there's no red light? Ordinary red pigments* look red because they reflect red light while absorbing all other wavelengths. At 20 metres down, there had to be some other explanation for the red Michiels was seeing. He suspected fluorescence. Fluorescent pigments behave differently from ordinary ones: they receive incoming light of one wavelength, for example blue, and emit light of a longer wavelength, in this case red. On the reef in the Red Sea during daytime, the most likely explanation was that the predominantly blue and green wavelengths at depth triggered the emission of fluorescent red in the fish.
D
With only a week left in Egypt, and lacking the equipment to confirm that the fish were fluorescent, Michiels photographed as many of them as he could. Then once back in Germany, he bought an assortment of tropical fish and installed them in his lab. Here he confirmed that the fish did indeed fluoresce. In most of the fish he looked at, the fluorescence could be traced to specialised pigment cells that lie in the skin beneath the scales. These cells contain 'guanine crystals', which scatter light to give fish their silvery sheen. However, Michiels says they are still not sure exactly what is fluorescing. 'It's not the crystals themselves. It's probably a fluorescent protein built into the crystals, and we have a suspicion that it might be made by bacteria.'
E
Intrigued, Michiels began a systematic search for red fluorescence in reef fish. He and his colleagues, Nils Anthes and Dennis Sprenger, have identified some 50 species with red fluorescence. The most common markings tend to be on the body towards the head and to a lesser extent around the eyes, and then the fins. To Michiels, the distribution of these markings is one of the strongest indications that red fluorescence has a very particular function: communication with other members of the species. According to several recent studies, a whole range of animals employ fluorescence as a natural highlighter to boost the visibility of body parts they use to signal, for example to ward off enemies. In reef fish, the red tends to be confined to parts of the body used to signal, suggesting these markings serve a similar function. But instead of highlighting an existing colour, the fluorescence gives the fish a colour that otherwise wouldn't exist. For example, fish commonly use eye rings to signal that they are present and their direction of gaze, and Michiels suspects that red-eyed gobies use signals to indicate their location and keep their group together.
F
Red light, whatever its source, doesn't travel far through water, which suggests signals are intended to be private, seen only by nearby fish of the right species. There are several lines of evidence to support this, says Michiels. And closely related species do not have completely identical markings, which suggests they might be important in species recognition.
G
Michiels suspects red fluorescence has another important role for some reef fish: helping them blend in. During his first dive with the red filter, he noticed corals glow a dark but faint red too. Against this irregular red background, a fish that glows red all over would be hard to distinguish. More compelling for Michiels is the case of the scorpionfish, which lies perfectly still until food swims past which it then sucks in.
H
Yet if red plays any part in a fish's life then it must be able to see it. Fish that live in a world dominated by blue-green light are assumed to have eyes tuned to those wavelengths, and most marine fish that have been studied are thought incapable of seeing red. One exception is the seahorse, whose eyes are sensitive to red. As for the other fish, it remains to be seen.
________________________
*pigments: a pigment is a substance that gives something a particular colour
🔥 Đáp án & giải thích 1
1
True
Giải thích chi tiết
☺️ Ứng dụng Linearthinking để giải quyết dạng bài True / False / Not Given
Step 01: Read the question to understand (main idea + detail)
Simplified: Michiels expected total darkness at about 15 metres during his 2007 dive
-------
Step 02: Locate relevant information
🔍 Từ khóa: “2007”, “15 metres”, “darkness”
=> Dựa vào các từ khoá trên -> Tìm được trích dẫn ở đoạn A.
-------
Step 03: Read relevant information to understand (main + detail)
📌 Trích dẫn: “In theory, once he reached about 15 metres, he should have been plunged into darkness.”
Simplified: he should have been plunged into darkness at about 15 metres
Main idea: Theo lý thuyết, khi xuống khoảng 15 mét, Michiels dự kiến sẽ rơi vào bóng tối.
-------
Step 04: Compare meaning with meaning
Trong bài đọc: Michiels dự kiến sẽ gặp bóng tối ở độ sâu khoảng 15 mét.
Trong câu hỏi: Michiels mong đợi gặp bóng tối hoàn toàn ở khoảng 15 mét trong lần lặn năm 2007.
→ Hai ýtương đương: cả hai đều nói về kỳ vọng ban đầu của Michiels về bóng tối ở độ sâu 15 mét.
⇒ ✅ Chọn: TRUE
-------
Lưu ý chung:
Nếu đáp án là FALSE: bài đọc phải nói rằng Michiels không mong đợi bóng tối ở độ sâu đó.
Nếu đáp án là NOT GIVEN: bài đọc sẽ không đề cập đến kỳ vọng của Michiels trước khi lặn.
A. The advisability of humans participating directly in space travel continues to cause many debates. There is no doubt that the presence of people on board a space vehicle makes its design much more complex and challenging, and produces a large increase in costs, since safety requirements are greatly increased, and the technology providing necessities for human passengers such as oxygen, food water must be guaranteed. Moreover, the systems required are bulky and costly, and their complexity increases for long-duration missions. Meanwhile, advances in electronics and computer science allow increasingly complex tasks to be entrusted to robots, and unmanned space probes are becoming lighter, smaller and more convenient.
B
However, experience has shown that the idea of humans in space is popular with the public. Humans can also be useful; there are many cases when only direct intervention by an astronaut or cosmonaut can correct the malfunction of an automatic device. Astronauts and cosmonauts have proved that they can adapt to conditions of weightlessness and work in space without encountering too many problems, as was seen in the operations to repair and to upgrade the Hubble Space Telescope. One human characteristic which is particularly precious in space missions, and which so far is lacking in robots, is the ability to perform a great variety of tasks. In addition, robots are not good at reacting to situations they have not been specifically prepared for. This is especially important in the case of deep space missions. While, in the case of the Moon, it is possible for someone on Earth to ‘tele-operate’ a robotic device such as a probe, as the two-way link time is only a couple of seconds, on Mars the two-way link time is several minutes, so sending instructions from Earth is more difficult.
C
Many of the promises of artificial intelligence are still far from being fulfilled. The construction of machines simulating human logical reasoning moves towards ever more distant dates. The more the performance of computers improves, the more we realise how difficult it is to build machines which display logical abilities. In the past it was confidently predicted that we would soon have fully automated factories in which all operations were performed without any human intervention, and forecasts of the complete substitution of workers by robots in many production areas were made. Today, these perspectives are being revised. It seems that all machines, even the smartest ones, must cooperate with humans. Rather than replacing humans, the present need appears to be for an intelligent machine capable of helping a human operator without replacing him or her. The word ‘cobot’, from ‘collaborative robot’, has been invented to designate this type.
D
A similar trend is also apparent in the field of space exploration. Tasks which were in the past entrusted only to machines are now performed by human beings, sometimes with the aim of using simpler and less costly devices, sometimes to obtain better performance. In many cases, to involve a person in the control loop is a welcome simplification which may lower the cost of a mission without compromising safety. Many operations originally designed to be performed under completely automatic control can be performed more efficiently by astronauts, perhaps helped by their ‘cobots’. The human-machine relationship must evolve towards a closer collaboration.
E
One way this could happen is by adopting the Mars Outposts approach, proposed by the Planetary Society. This would involve sending a number of robotic research stations to Mars, equipped with permanent communications and navigational systems. They would perform research, and establish the infrastructure needed to prepare future landing sites for the exploration of Mars by humans. It has also been suggested that in the most difficult environments, as on Venus or Jupiter, robots could be controlled by human beings located in spaceships which remain in orbit around the planet. In this case the link time for communication between humans and robots would be far less than it would be from Earth.
F
But if space is to be more than a place to build automatic laboratories or set up industrial enterprises in the vicinity of our planet, the presence of humans is essential. They must learn how to voyage through space towards destinations which will be not only scientific bases but also places to live. If space is a frontier, that frontier must see the presence of people. So the aim for humankind in the future will be not just the exploration of space, but its colonisation. The result of exploring and living in space may be a deep change in the views which humankind has of itself. And this process is already under way. The images of Earth taken from the Moon in the Apollo programme have given humankind a new consciousness of its fragility, its smallness, and its unity. These impressions have triggered a realisation of the need to protect and preserve it, for it is the place in the solar system most suitable for the US and above all it is the only place we have, at least for now.
🔥 Đáp án & giải thích 2
14
VI
Giải thích chi tiết
☺️ Ứng dụng Linearthinking để giải quyết dạng bài Matching Headings
✅ Paragraph A → Đáp án đúng: F. Problems in using humans for space exploration
-------
Giải thích chi tiết
Step 01: Read to understand main idea
Dựa vào Simplify & Connection phía trên ta rút ra đại ý:
Đoạn A nhấn mạnh nhược điểm của việc đưa con người lên tàu vũ trụ: làm thiết kế phức tạp, tăng yêu cầu an toàn, phải cung cấp/đảm bảo oxy–đồ ăn–nước, hệ thống cồng kềnh và đặc biệt bất lợi cho nhiệm vụ dài ngày.
Sau đó đối chiếu rằng robot/probe ngày càng tiện hơn.
⇒ Main idea: Việc dùng humans trong khám phá không gian gây nhiều khó khăn và chi phí.
-------
Step 02: Compare meaning with meaning
Đại ý đoạn A:Con người tham gia trực tiếp khiến nhiệm vụ không gian trở nên phức tạp, đắt đỏ, nặng về yêu cầu an toàn và hậu cần (nhu yếu phẩm), nhất là với chuyến bay dài.
So với các headings, ý này khớp nhất với F. Problems in using humans for space exploration.
✅ Paragraph A → Đáp án đúng: F. Problems in using humans for space exploration
The long-standing debate about whether to fluoridate our drinking water continues. Fluoridation is the addition of fluorine to public water supplies with the aim of reducing tooth decay. The fluorine, when mixed with water, becomes fluoride and the desired concentration of fluoride in public water is approximately one part per million, depending on the regional temperature and hence the amount of water people are likely to drink. Many studies, such as those by McClure in 1970 through to Burt in 1983, have shown that when children drink fluoridated water, their average rate of tooth decay seems greatly reduced. A typical figure claimed is 50 percent reduction. This apparently enormous benefit for children's teeth is the major argument in favor of fluoridation.
Three main grounds for opposition to fluoridation have been expressed. First, opponents claim the benefits are exaggerated or not established. Second, there are claims of health risks to pans of the population, for example, allergic reactions. It is also accepted that high levels of fluoride can cause discoloration of otherwise healthy teeth. Proponents do not consider this to be a problem in such small concentrations, whereas opponents disagree - especially because some people drink more water and obtain much more than the standard milligram of fluoride per day. Third, fluoridation is thought to be an infringement on individual rights because it is compulsory medication for all members of a community.
An understanding of the fluoridation issue has important implications. If, according to the experts, fluoridation is unquestionably a beneficial and non-hazardous measure, then the wisdom of allowing the public to vote on, and reject it must be questioned.
Almost all studies that have been done have assumed that the scientific aspects of the controversy are unproblematic, and they have excluded science from sociological examination. The traditional view is that science is a special kind of knowledge, which is established through scientific methods and objectively applied by members of a scientific community. However, in recent years there has been a major challenge to this picture by a sociology of science that shows how scientific knowledge is socially negotiated, and inevitably linked to the values of the relevant parties, both scientists and nonscientists. These challengers do not see scientific knowledge as exempt from social inquiry.
Kuhn (1970) argued that scientific knowledge does not always develop as an orderly process, but is characterized by periodic revolutions. in which the methods of study and the assessment criteria change in a fragmented way. According to Kuhn, the shift from one scientific way of thinking to another is not made solely on the basis of clear rules of formal scientific practice, but can include social factors, though Kuhn has never developed a full analysis of what these might be. Collins (1975) took this concept further when he asserted that the outcome of experiments was not something whose meaning could be immediately comprehended, but rather something for interpretation, discussion between scientists, and reinterpretation in the light of other experiments.
One interpretation of this analysis of science is that traditional distinctions between facts and theories, and between scientific knowledge and values, can no longer be justified. Because social processes are involved at all stages of the creation, evaluation, and establishing of scientific knowledge, social values may also be involved.
In the same way as many scientists who study fluoridation have overlooked social values, sociologists have also downplayed an important part of the debate by ignoring the number of eminent scientists who have questioned aspects of fluoridation. An example is the study by Sutton in 1960, which analyzed the classic North American studies of the effect of fluoridation on tooth decay, and found that each showed significant methodological shortcomings. Sutton's detailed study throws doubt as to the extent of reductions in tooth decay from fluoridation. Yet Sutton's book is not cited in a single analysis of the fluoridation issue by any sociologist. In a situation of some scientific uncertainty, differences in values are highlighted. A supporter of fluoridation might argue, 'The evidence for the benefits of fluoridation is quite substantial, while the evidence for harm is limited and dubious. I think the likely benefits outweigh the possible dangers; hence I support fluoridation because it is the cheapest and easiest way to make sure every child reaps the benefits.' An opponent might argue, 'Though the evidence for the benefits of fluoridation is substantial, there is some doubt about it. Since fluoridation is not necessary for good teeth, we should forego the benefits if there is some slight chance of harm. Some scientists claim that a small percentage of the population could be harmed by fluoride. Therefore I oppose fluoridation of water supplies and favor the voluntary use of fluoride tablets by those who want to take them.'
Both arguments consider the scientific evidence concerning fluoridation, but differ in their assessments of the social benefits and costs. This difference is not between rationality and irrationality but is a legitimate difference in values, for example, the positive value placed on good teeth, the negative value placed on possible health risks, and the social benefits or costs of compulsory or voluntary intake of fluorides.
From the sociological point of view, opposition to fluoridation is not necessarily irrational. Rather, claims to rationality and to scientific authority are better seen as part of a strategy to promote fluoridation than as incontrovertible statements of fact. Second, social values are likely to be bound up in any decision about fluoridation, so this is not an issue on which declarations by scientific experts ought to be considered the final word.
🔥 Đáp án & giải thích 3
27
A
Giải thích chi tiết
☺️ Ứng dụng Linearthinking để giải quyết dạng bài Multiple Choice
Step 01: Read the question to understand (main idea + detail)
Simplified: the optimum amount of fluoride is calculated partly according to ...
Main idea: Câu hỏi hỏi yếu tố nào được dùng để tính toán lượng fluoride phù hợp trong nước uống có bổ sung fluoride.
-------
Step 02: Locate relevant information
🔍 Từ khoá: “fluoride”, “hot/warm“, “temperature”, “dental problems”, “water”
=> Dựa vào các từ khoá trên -> Tìm được trích dẫn ở đoạn 1.
-------
Step 03: Read relevant information to understand (main + detail)
📌 Trích dẫn: “the desired concentration of fluoride in public water is approximately one part per million, depending on the regional temperature and hence the amount of water people are likely to drink.”
Simplified: the desired concentration of fluoride depends on regional temperature and hence the amount of water people drink
Main idea: Nơi khí hậu nóng hơn → người dân uống nhiều nước hơn → cần điều chỉnh lượng fluoride cho phù hợp.
-------
Step 04: Compare meaning with meaning
✅ A. how hot the area is.: Đúng vì “regional temperature” trực tiếp nói đến mức độ nóng của khu vực, là yếu tố được dùng để tính lượng fluoride.
❌ B. how warm the water is.: Sai vì đoạn văn nói về nhiệt độ khu vực, không phải nhiệt độ của nước.
❌ C. how many dental problems there are in the community.: Sai vì không có chỗ nào nói việc tính nồng độ dựa trên số vấn đề răng miệng của cộng đồng.
❌ D. how much fluorine the community chooses to have in its water.: Sai vì đây không phải quyết định chủ quan của cộng đồng; nồng độ được tính toán khoa học.
Nico Michiels is an ecologist from the University of Tubingen in Germany who spends part of each year in Egypt, where he dives in the Red Sea, observing fish life and gathering data on its coral reefs. In September 2007 he decided to find out how far red light could penetrate the ocean depths. Seawater absorbs different colours at different depths, and as an experienced diver, Michiels was aware that red light is extinguished not far below the surface whereas blue-green light penetrates deeper. To find out the depth at which red disappeared in this particular ocean, however, he attached a special plastic filter to his dive mask which was designed to block out all colours except red. Then he began to descend. In theory, once he reached about 15 metres, he should have been plunged into darkness. Instead, something totally unexpected happened. Sure enough, 20 metres down it was as dark as night. 'All the fish disappeared. With no light from the surface, they were effectively black and had become invisible,' he says. 'But it didn't stay black for long. Then I saw a group of goby fish with bright red eyes lit up against the background. After that red spots began to show up all over the reef.'
C. But how can fish appear red where there's no red light? Ordinary red pigments* look red because they reflect red light while absorbing all other wavelengths. At 20 metres down, there had to be some other explanation for the red Michiels was seeing. He suspected fluorescence. Fluorescent pigments behave differently from ordinary ones: they receive incoming light of one wavelength, for example blue, and emit light of a longer wavelength, in this case red. On the reef in the Red Sea during daytime, the most likely explanation was that the predominantly blue and green wavelengths at depth triggered the emission of fluorescent red in the fish.
D. With only a week left in Egypt, and lacking the equipment to confirm that the fish were fluorescent, Michiels photographed as many of them as he could. Then once back in Germany, he bought an assortment of tropical fish and installed them in his lab. Here he confirmed that the fish did indeed fluoresce. In most of the fish he looked at, the fluorescence could be traced to specialised pigment cells that lie in the skin beneath the scales. These cells contain 'guanine crystals', which scatter light to give fish their silvery sheen. However, Michiels says they are still not sure exactly what is fluorescing. 'It's not the crystals themselves. It's probably a fluorescent protein built into the crystals, and we have a suspicion that it might be made by bacteria.'
E. Intrigued, Michiels began a systematic search for red fluorescence in reef fish. He and his colleagues, Nils Anthes and Dennis Sprenger, have identified some 50 species with red fluorescence. The most common markings tend to be on the body towards the head and to a lesser extent around the eyes, and then the fins. To Michiels, the distribution of these markings is one of the strongest indications that red fluorescence has a very particular function: communication with other members of the species. According to several recent studies, a whole range of animals employ fluorescence as a natural highlighter to boost the visibility of body parts they use to signal, for example to ward off enemies. In reef fish, the red tends to be confined to parts of the body used to signal, suggesting these markings serve a similar function. But instead of highlighting an existing colour, the fluorescence gives the fish a colour that otherwise wouldn't exist. For example, fish commonly use eye rings to signal that they are present and their direction of gaze, and Michiels suspects that red-eyed gobies use signals to indicate their location and keep their group together.
F. Red light, whatever its source, doesn't travel far through water, which suggests signals are intended to be private, seen only by nearby fish of the right species. There are several lines of evidence to support this, says Michiels. And closely related species do not have completely identical markings, which suggests they might be important in species recognition.
G. Michiels suspects red fluorescence has another important role for some reef fish: helping them blend in. During his first dive with the red filter, he noticed corals glow a dark but faint red too. Against this irregular red background, a fish that glows red all over would be hard to distinguish. More compelling for Michiels is the case of the scorpionfish, which lies perfectly still until food swims past which it then sucks in.
H. Yet if red plays any part in a fish's life then it must be able to see it. Fish that live in a world dominated by blue-green light are assumed to have eyes tuned to those wavelengths, and most marine fish that have been studied are thought incapable of seeing red. One exception is the seahorse, whose eyes are sensitive to red. As for the other fish, it remains to be seen.
________________________
*pigments: a pigment is a substance that gives something a particular colour
he
should have been plunged into darkness
at about 15 metres
Main idea: Theo lý thuyết, khi xuống khoảng 15 mét, Michiels dự kiến sẽ rơi vào bóng tối.
B. However, experience has shown that the idea of humans in space is popular with the public. Humans can also be useful; there are many cases when only direct intervention by an astronaut or cosmonaut can correct the malfunction of an automatic device. Astronauts and cosmonauts have proved that they can adapt to conditions of weightlessness and work in space without encountering too many problems, as was seen in the operations to repair and to upgrade the Hubble Space Telescope. One human characteristic which is particularly precious in space missions, and which so far is lacking in robots, is the ability to perform a great variety of tasks. In addition, robots are not good at reacting to situations they have not been specifically prepared for. This is especially important in the case of deep space missions. While, in the case of the Moon, it is possible for someone on Earth to ‘tele-operate’ a robotic device such as a probe, as the two-way link time is only a couple of seconds, on Mars the two-way link time is several minutes, so sending instructions from Earth is more difficult.
C. Many of the promises of artificial intelligence are still far from being fulfilled. The construction of machines simulating human logical reasoning moves towards ever more distant dates. The more the performance of computers improves, the more we realise how difficult it is to build machines which display logical abilities. In the past it was confidently predicted that we would soon have fully automated factories in which all operations were performed without any human intervention, and forecasts of the complete substitution of workers by robots in many production areas were made. Today, these perspectives are being revised. It seems that all machines, even the smartest ones, must cooperate with humans. Rather than replacing humans, the present need appears to be for an intelligent machine capable of helping a human operator without replacing him or her. The word ‘cobot’, from ‘collaborative robot’, has been invented to designate this type.
D. A similar trend is also apparent in the field of space exploration. Tasks which were in the past entrusted only to machines are now performed by human beings, sometimes with the aim of using simpler and less costly devices, sometimes to obtain better performance. In many cases, to involve a person in the control loop is a welcome simplification which may lower the cost of a mission without compromising safety. Many operations originally designed to be performed under completely automatic control can be performed more efficiently by astronauts, perhaps helped by their ‘cobots’. The human-machine relationship must evolve towards a closer collaboration.
E. One way this could happen is by adopting the Mars Outposts approach, proposed by the Planetary Society. This would involve sending a number of robotic research stations to Mars, equipped with permanent communications and navigational systems. They would perform research, and establish the infrastructure needed to prepare future landing sites for the exploration of Mars by humans. It has also been suggested that in the most difficult environments, as on Venus or Jupiter, robots could be controlled by human beings located in spaceships which remain in orbit around the planet. In this case the link time for communication between humans and robots would be far less than it would be from Earth.
F. But if space is to be more than a place to build automatic laboratories or set up industrial enterprises in the vicinity of our planet, the presence of humans is essential. They must learn how to voyage through space towards destinations which will be not only scientific bases but also places to live. If space is a frontier, that frontier must see the presence of people. So the aim for humankind in the future will be not just the exploration of space, but its colonisation. The result of exploring and living in space may be a deep change in the views which humankind has of itself. And this process is already under way. The images of Earth taken from the Moon in the Apollo programme have given humankind a new consciousness of its fragility, its smallness, and its unity. These impressions have triggered a realisation of the need to protect and preserve it, for it is the place in the solar system most suitable for the US and above all it is the only place we have, at least for now.
The long-standing debate about whether to fluoridate our drinking water continues. Fluoridation is the addition of fluorine to public water supplies with the aim of reducing tooth decay. The fluorine, when mixed with water, becomes fluoride and the desired concentration of fluoride in public water is approximately one part per million, depending on the regional temperature and hence the amount of water people are likely to drink. Many studies, such as those by McClure in 1970 through to Burt in 1983, have shown that when children drink fluoridated water, their average rate of tooth decay seems greatly reduced. A typical figure claimed is 50 percent reduction. This apparently enormous benefit for children's teeth is the major argument in favor of fluoridation.
Three main grounds for opposition to fluoridation have been expressed. First, opponents claim the benefits are exaggerated or not established. Second, there are claims of health risks to pans of the population, for example, allergic reactions. It is also accepted that high levels of fluoride can cause discoloration of otherwise healthy teeth. Proponents do not consider this to be a problem in such small concentrations, whereas opponents disagree - especially because some people drink more water and obtain much more than the standard milligram of fluoride per day. Third, fluoridation is thought to be an infringement on individual rights because it is compulsory medication for all members of a community.
An understanding of the fluoridation issue has important implications. If, according to the experts, fluoridation is unquestionably a beneficial and non-hazardous measure, then the wisdom of allowing the public to vote on, and reject it must be questioned.
Almost all studies that have been done have assumed that the scientific aspects of the controversy are unproblematic, and they have excluded science from sociological examination. The traditional view is that science is a special kind of knowledge, which is established through scientific methods and objectively applied by members of a scientific community. However, in recent years there has been a major challenge to this picture by a sociology of science that shows how scientific knowledge is socially negotiated, and inevitably linked to the values of the relevant parties, both scientists and nonscientists. These challengers do not see scientific knowledge as exempt from social inquiry.
Kuhn (1970) argued that scientific knowledge does not always develop as an orderly process, but is characterized by periodic revolutions. in which the methods of study and the assessment criteria change in a fragmented way. According to Kuhn, the shift from one scientific way of thinking to another is not made solely on the basis of clear rules of formal scientific practice, but can include social factors, though Kuhn has never developed a full analysis of what these might be. Collins (1975) took this concept further when he asserted that the outcome of experiments was not something whose meaning could be immediately comprehended, but rather something for interpretation, discussion between scientists, and reinterpretation in the light of other experiments.
One interpretation of this analysis of science is that traditional distinctions between facts and theories, and between scientific knowledge and values, can no longer be justified. Because social processes are involved at all stages of the creation, evaluation, and establishing of scientific knowledge, social values may also be involved.
In the same way as many scientists who study fluoridation have overlooked social values, sociologists have also downplayed an important part of the debate by ignoring the number of eminent scientists who have questioned aspects of fluoridation. An example is the study by Sutton in 1960, which analyzed the classic North American studies of the effect of fluoridation on tooth decay, and found that each showed significant methodological shortcomings. Sutton's detailed study throws doubt as to the extent of reductions in tooth decay from fluoridation. Yet Sutton's book is not cited in a single analysis of the fluoridation issue by any sociologist. In a situation of some scientific uncertainty, differences in values are highlighted. A supporter of fluoridation might argue, 'The evidence for the benefits of fluoridation is quite substantial, while the evidence for harm is limited and dubious. I think the likely benefits outweigh the possible dangers; hence I support fluoridation because it is the cheapest and easiest way to make sure every child reaps the benefits.' An opponent might argue, 'Though the evidence for the benefits of fluoridation is substantial, there is some doubt about it. Since fluoridation is not necessary for good teeth, we should forego the benefits if there is some slight chance of harm. Some scientists claim that a small percentage of the population could be harmed by fluoride. Therefore I oppose fluoridation of water supplies and favor the voluntary use of fluoride tablets by those who want to take them.'
Both arguments consider the scientific evidence concerning fluoridation, but differ in their assessments of the social benefits and costs. This difference is not between rationality and irrationality but is a legitimate difference in values, for example, the positive value placed on good teeth, the negative value placed on possible health risks, and the social benefits or costs of compulsory or voluntary intake of fluorides.
From the sociological point of view, opposition to fluoridation is not necessarily irrational. Rather, claims to rationality and to scientific authority are better seen as part of a strategy to promote fluoridation than as incontrovertible statements of fact. Second, social values are likely to be bound up in any decision about fluoridation, so this is not an issue on which declarations by scientific experts ought to be considered the final word.
depends on
regional temperature
and hence
the amount of water people drink
Main idea: Nơi khí hậu nóng hơn → người dân uống nhiều nước hơn → cần điều chỉnh lượng fluoride cho phù hợp.
The long-standing debate about whether to fluoridate our drinking water continues. Fluoridation is the addition of fluorine to public water supplies with the aim of reducing tooth decay. The fluorine, when mixed with water, becomes fluoride and the desired concentration of fluoride in public water is approximately one part per million, depending on the regional temperature and hence the amount of water people are likely to drink. Many studies, such as those by McClure in 1970 through to Burt in 1983, have shown that when children drink fluoridated water, their average rate of tooth decay seems greatly reduced. A typical figure claimed is 50 percent reduction. This apparently enormous benefit for children's teeth is the major argument in favor of fluoridation.
Three main grounds for opposition to fluoridation have been expressed. First, opponents claim the benefits are exaggerated or not established. Second, there are claims of health risks to pans of the population, for example, allergic reactions. It is also accepted that high levels of fluoride can cause discoloration of otherwise healthy teeth. Proponents do not consider this to be a problem in such small concentrations, whereas opponents disagree - especially because some people drink more water and obtain much more than the standard milligram of fluoride per day. Third, fluoridation is thought to be an infringement on individual rights because it is compulsory medication for all members of a community.
An understanding of the fluoridation issue has important implications. If, according to the experts, fluoridation is unquestionably a beneficial and non-hazardous measure, then the wisdom of allowing the public to vote on, and reject it must be questioned.
Almost all studies that have been done have assumed that the scientific aspects of the controversy are unproblematic, and they have excluded science from sociological examination. The traditional view is that science is a special kind of knowledge, which is established through scientific methods and objectively applied by members of a scientific community. However, in recent years there has been a major challenge to this picture by a sociology of science that shows how scientific knowledge is socially negotiated, and inevitably linked to the values of the relevant parties, both scientists and nonscientists. These challengers do not see scientific knowledge as exempt from social inquiry.
Kuhn (1970) argued that scientific knowledge does not always develop as an orderly process, but is characterized by periodic revolutions. in which the methods of study and the assessment criteria change in a fragmented way. According to Kuhn, the shift from one scientific way of thinking to another is not made solely on the basis of clear rules of formal scientific practice, but can include social factors, though Kuhn has never developed a full analysis of what these might be. Collins (1975) took this concept further when he asserted that the outcome of experiments was not something whose meaning could be immediately comprehended, but rather something for interpretation, discussion between scientists, and reinterpretation in the light of other experiments.
One interpretation of this analysis of science is that traditional distinctions between facts and theories, and between scientific knowledge and values, can no longer be justified. Because social processes are involved at all stages of the creation, evaluation, and establishing of scientific knowledge, social values may also be involved.
In the same way as many scientists who study fluoridation have overlooked social values, sociologists have also downplayed an important part of the debate by ignoring the number of eminent scientists who have questioned aspects of fluoridation. An example is the study by Sutton in 1960, which analyzed the classic North American studies of the effect of fluoridation on tooth decay, and found that each showed significant methodological shortcomings. Sutton's detailed study throws doubt as to the extent of reductions in tooth decay from fluoridation. Yet Sutton's book is not cited in a single analysis of the fluoridation issue by any sociologist. In a situation of some scientific uncertainty, differences in values are highlighted. A supporter of fluoridation might argue, 'The evidence for the benefits of fluoridation is quite substantial, while the evidence for harm is limited and dubious. I think the likely benefits outweigh the possible dangers; hence I support fluoridation because it is the cheapest and easiest way to make sure every child reaps the benefits.' An opponent might argue, 'Though the evidence for the benefits of fluoridation is substantial, there is some doubt about it. Since fluoridation is not necessary for good teeth, we should forego the benefits if there is some slight chance of harm. Some scientists claim that a small percentage of the population could be harmed by fluoride. Therefore I oppose fluoridation of water supplies and favor the voluntary use of fluoride tablets by those who want to take them.'
Both arguments consider the scientific evidence concerning fluoridation, but differ in their assessments of the social benefits and costs. This difference is not between rationality and irrationality but is a legitimate difference in values, for example, the positive value placed on good teeth, the negative value placed on possible health risks, and the social benefits or costs of compulsory or voluntary intake of fluorides.
From the sociological point of view, opposition to fluoridation is not necessarily irrational. Rather, claims to rationality and to scientific authority are better seen as part of a strategy to promote fluoridation than as incontrovertible statements of fact. Second, social values are likely to be bound up in any decision about fluoridation, so this is not an issue on which declarations by scientific experts ought to be considered the final word.
