Cambridge 20 Test 3 Reading Answers & Explanations

This post provides complete answers and clear explanations for Cambridge IELTS 20 Academic Reading Test 3.

Each answer includes:

• Strategy
• Keywords
• Exact paragraph and line location
• Explanation
• Correct answer

> Location note: The paragraph and line locations below refer to the supplied Cambridge 20 Reading Test 3 material.

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How This Guide Is Structured

Strategy

The strategy explains the best method for solving each IELTS Reading question type.

Keywords

Keywords are the important words and phrases that help you locate the relevant information quickly.

Exact Paragraph and Line Location

Each answer identifies the relevant passage, paragraph or section, and line range.

Explanation

The explanation shows how the question matches, paraphrases or contradicts the passage.

Correct Answer

The final answer appears after the explanation.

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Reading Passage 1

Frozen Food

Questions 1–7: Note Completion

Strategy

For note-completion questions:

1. Read the complete notes before scanning.
2. Use dates as location markers.
3. Predict the type of word required.
4. Scan for the same event in the passage.
5. Look for paraphrases.
6. Copy the exact word from the passage.
7. Follow the word limit strictly.

The instruction says:

Choose ONE WORD ONLY from the passage for each answer.

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Question 1

People in South America conserved the nutritional value of ______ by freezing and drying them.

Keywords

2,000 years ago, South America, nutritional value, freezing, drying

Exact Paragraph and Line Location

Reading Passage 1, Paragraph 1, lines 6–11

Explanation

People living in the Andean mountains froze potatoes overnight, removed their moisture and then dried them in the sun.

The process preserved their nutritional value.

So, the answer is: potatoes

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Question 2

______ was kept cool by ice while being transported in specially adapted trains.

Keywords

1851, transportation, rail cars, ice

Exact Paragraph and Line Location

Reading Passage 1, Paragraph 2, lines 12–15

Explanation

In 1851, railroads began putting blocks of ice in insulated railway cars to transport butter from New York to Boston.

So, the answer is: butter

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Question 3

Two kinds of ______ were the first frozen food shipped from Australia to England.

Keywords

1880, Australia, England, beef, mutton

Exact Paragraph and Line Location

Reading Passage 1, Paragraph 4, lines 21–26

Explanation

The passage says Australian cattlemen realised refrigeration could allow them to export meat.

In 1880, frozen beef and mutton were shipped to England.

Both are types of meat.

So, the answer is: meat

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Question 4

Birdseye developed quick-freezing methods so that ______ did not spoil the food.

Keywords

Birdseye, quick-freezing, damage, spoil food

Exact Paragraph and Line Location

Reading Passage 1, Paragraph 6, lines 38–40

Explanation

Earlier freezing methods caused crystals to form inside the cells of food and damage its flavour and texture.

Birdseye developed quick-freezing techniques that reduced this damage.

So, the answer is: crystals

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Question 5

Products were packaged with ______ so consumers could see the food.

Keywords

packaging, transparent, see product

Exact Paragraph and Line Location

Reading Passage 1, Paragraph 6, lines 40–43

Explanation

Birdseye introduced cellophane as a transparent packaging material.

This allowed consumers to see the quality of the product.

So, the answer is: cellophane

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Question 6

Frozen food became more popular because of a shortage of ______.

Keywords

early 1940s, World War II, shortage, canned food

Exact Paragraph and Line Location

Reading Passage 1, Paragraph 8, lines 49–51

Explanation

During World War II, tin was needed for munitions.

Canned food was therefore rationed to conserve tin, while frozen food remained cheap and widely available.

So, the answer is: tin

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Question 7

By the 1950s, many homes had a ______.

Keywords

1950s, homes, appliance, families

Exact Paragraph and Line Location

Reading Passage 1, Paragraph 8, lines 51–54

Explanation

Refrigerator technology became affordable for ordinary families.

By 1953, around 33 million American families owned one.

So, the answer is: refrigerator

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Questions 8–13: TRUE, FALSE, NOT GIVEN

Strategy

For this question type:

• TRUE = the statement agrees with the passage.
• FALSE = the passage gives opposite information.
• NOT GIVEN = there is not enough information to decide.

Do not add information from your own knowledge.

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Question 8

Transporting ice made some Boston ship owners very wealthy in the early 1800s.

Keywords

Boston ship owners, wealthy, ice, early 1800s

Exact Paragraph and Line Location

Reading Passage 1, Paragraph 2, lines 12–15

Explanation

The passage says Boston ship owners transported enormous blocks of Arctic ice across the Atlantic.

However, it does not say whether this business made them wealthy.

So, the answer is: NOT GIVEN

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Question 9

The Australian freezing process negatively affected the taste of food.

Keywords

Australian process, taste, disadvantage, deterioration

Exact Paragraph and Line Location

Reading Passage 1, Paragraph 4, lines 23–26

Explanation

The food remained edible, but ice crystals damaged the cells.

This spoiled both its flavour and texture.

Here:

• flavour = taste
• spoilt = negatively affected

So, the answer is: TRUE

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Question 10

Clarence Birdseye went to Labrador specifically to learn how the Inuit froze fish.

Keywords

Birdseye, Labrador, Inuit, purpose

Exact Paragraph and Line Location

Reading Passage 1, Paragraph 5, lines 27–34

Explanation

Birdseye went to Labrador because he had run out of money and wanted to trap and trade furs.

He only became interested in the Inuit freezing technique after arriving.

Therefore, learning how fish were frozen was not the reason for his trip.

So, the answer is: FALSE

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Question 11

Swanson Foods spent a large amount of money promoting the TV Dinner.

Keywords

Swanson, TV Dinner, money, advertising

Exact Paragraph and Line Location

Reading Passage 1, Paragraph 9, lines 55–60

Explanation

The product was launched with a huge advertising budget.

Here:

• huge advertising budget = large amount of money spent on promotion

So, the answer is: TRUE

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Question 12

Swanson Foods created a new container specifically for the TV Dinner.

Keywords

new container, tray, TV Dinner

Exact Paragraph and Line Location

Reading Passage 1, Paragraph 9, lines 57–60

Explanation

The TV Dinner used the same type of segmented aluminium tray already used by airlines.

Therefore, Swanson did not develop a completely new container.

So, the answer is: FALSE

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Question 13

The US currently has the world's largest frozen food industry.

Keywords

US, largest in world, frozen food industry

Exact Paragraph and Line Location

Reading Passage 1, Paragraph 10, lines 68–71

Explanation

The passage gives the annual value of the US frozen food industry.

However, it does not compare the US industry with industries in other countries.

So, the answer is: NOT GIVEN

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Reading Passage 2

Can the Planet’s Coral Reefs Be Saved?

Questions 14–19: Matching Headings

Strategy

For matching-headings questions:

1. Read all headings before reading the sections.
2. Identify the main idea of each section.
3. Ignore examples unless they represent the whole paragraph.
4. Match the overall purpose, not individual keywords.
5. Use each heading only as instructed.

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Question 14 — Section A

Keywords

London Zoo, show people, conservation, research

Exact Paragraph and Line Location

Reading Passage 2, Section A, lines 139–150

Explanation

London Zoo’s coral exhibition has two main purposes:

• to show visitors how remarkable coral reefs are;
• to highlight research and conservation work designed to save them.

These are two clear educational aims.

So, the answer is: v — Two clear educational goals

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Question 15 — Section B

Keywords

coral, algae, relationship, protection, nutrients

Exact Paragraph and Line Location

Reading Passage 2, Section B, lines 152–158

Explanation

Coral polyps and algae help each other:

• the algae receive protection;
• the polyps receive nutrients produced through photosynthesis.

This is cooperation between two organisms living together.

So, the answer is: ii — Cooperation beneath the waves

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Question 16 — Section C

Keywords

rainforests of the sea, Attenborough, comparison

Exact Paragraph and Line Location

Reading Passage 2, Section C, lines 160–169

Explanation

Coral reefs are often called the rainforests of the sea.

David Attenborough challenges the usual comparison and argues that coral reefs can be even more spectacular.

The section therefore focuses on disagreement about the accuracy of a familiar description.

So, the answer is: iv — Disagreement about the accuracy of a certain phrase

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Question 17 — Section D

Keywords

threat, bleaching, 2050, coral loss

Exact Paragraph and Line Location

Reading Passage 2, Section D, lines 171–182

Explanation

The section lists serious threats including:

• rising temperatures;
• acidification;
• pollution;
• changing currents;
• habitat destruction.

Scientists warn that more than 90% of reefs could disappear by 2050 without urgent action.

So, the answer is: vii — A warning of further trouble ahead

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Question 18 — Section E

Keywords

scientists, hardy coral, breeding, restoration

Exact Paragraph and Line Location

Reading Passage 2, Section E, lines 184–191

Explanation

Researchers are trying to:

• identify coral species able to survive warmer and more acidic oceans;
• increase coral breeding rates.

These are practical attempts to reduce the problem.

So, the answer is: iii — Working to lessen the problems

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Question 19 — Section F

Keywords

public, progress, believe, save reefs

Exact Paragraph and Line Location

Reading Passage 2, Section F, lines 198–203

Explanation

Research progress can be shown to visitors to demonstrate that action can still be taken to save coral reefs.

The aim is to give people confidence and hope.

So, the answer is: vi — Promoting hope

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Questions 20–21: Choose TWO Answers

Strategy

1. Read all five options.
2. Scan the paragraph listing threats.
3. Match ideas rather than exact words.
4. Select exactly two answers.

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Questions 20–21

Which TWO causes of coral reef damage are mentioned?

Keywords

damage, pollution, water flow, threats

Exact Paragraph and Line Location

Reading Passage 2, Section D, lines 171–178

Explanation

The passage lists:

• pollution caused by humans;
• changes in ocean currents.

These correspond to:

• C — contamination of the sea from waste
• E — alterations in the usual flow of water in the seas

The passage does not specifically mention overfishing, increasing marine disease or a rising number of extreme storms.

So, the answers are: C and E

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Questions 22–23: Choose TWO Answers

Questions 22–23

Which TWO statements are true about researchers at London Zoo?

Keywords

London Zoo, research, warm water, breeding rates

Exact Paragraph and Line Location

Reading Passage 2, Section E, lines 184–191

Explanation

Researchers have two relevant aims.

First, they want to identify coral species that survive best in warmer, more acidic water.

Second, they want to increase coral breeding rates.

Therefore:

• B — They want to identify corals that can cope well with changed sea conditions.
• D — They are trying methods that could speed up reproduction in some corals.

So, the answers are: B and D

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Questions 24–26: Sentence Completion

Strategy

For sentence completion:

1. Predict the grammar of the missing word.
2. Locate the matching idea.
3. Copy the exact word.
4. Check the one-word limit.

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Question 24

Corals have a number of ______ which they use to collect food.

Keywords

corals, collect food, polyps

Exact Paragraph and Line Location

Reading Passage 2, Section B, lines 152–155

Explanation

Coral polyps have tentacles which they use to capture small marine creatures.

So, the answer is: tentacles

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Question 25

Algae gain ______ from being inside the coral.

Keywords

algae, inside coral, benefit

Exact Paragraph and Line Location

Reading Passage 2, Section B, lines 152–156

Explanation

The algae live inside the coral polyps and receive protection.

In return, they provide nutrients to the coral.

So, the answer is: protection

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Question 26

Rising sea temperatures can remove the ______ from coral.

Keywords

rising temperatures, bleaching, remove

Exact Paragraph and Line Location

Reading Passage 2, Section D, lines 171–174

Explanation

Higher ocean temperatures cause bleaching events that strip reefs of their colour.

Here:

• strip ... of = remove
• The thing removed is colour.

Both British and American spellings may be accepted.

So, the answer is: colour / color

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Reading Passage 3

Robots and Us

Questions 27–33: Matching Experts

Strategy

For matching-expert questions:

1. Learn the three speakers:
   • A — Martin Rees
   • B — Daniel Wolpert
   • C — Kathleen Richardson
2. Identify the central idea in the statement.
3. Locate which expert expresses that opinion.
4. Match meaning rather than vocabulary.
5. Remember that a letter may be used more than once.

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Question 27

Humans should restrict robot abilities for our own safety.

Keywords

restrict abilities, safety, outwit humans

Exact Paragraph and Line Location

Reading Passage 3, Martin Rees on AI risk, lines 297–302

Explanation

Rees says robots should remain limited and should not have the capacity to outwit humans.

This directly supports the statement.

So, the answer is: A — Martin Rees

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Question 28

The danger of robots harming humans is less serious than people believe.

Keywords

robots, threat, humans, fear

Exact Paragraph and Line Location

Reading Passage 3, Kathleen Richardson on AI risk, lines 308–311

Explanation

Richardson says robots have never actually challenged human supremacy and believes it is unlikely they ever will.

She therefore considers the perceived threat exaggerated.

So, the answer is: C — Kathleen Richardson

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Question 29

It will take many decades for machine intelligence to become as creative as human intelligence.

Keywords

many decades, creative intelligence, human

Exact Paragraph and Line Location

Reading Passage 3, Daniel Wolpert on machine intelligence, lines 281–289

Explanation

Wolpert says expecting a machine to achieve something close to human creative intelligence within the next 50 years would be highly ambitious.

So, the answer is: B — Daniel Wolpert

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Question 30

We may eventually need to consider whether sophisticated robots are treated fairly.

Keywords

fairly, ethical treatment, sophisticated robots

Exact Paragraph and Line Location

Reading Passage 3, Martin Rees on machine intelligence, lines 274–280

Explanation

Rees asks whether humans should feel guilty about exploiting advanced robots and whether we should worry if they become frustrated or bored.

These are questions about fair and ethical treatment.

So, the answer is: A — Martin Rees

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Question 31

Robots may be more useful to humans on Earth than in space.

Keywords

Earth, space, resources, better use

Exact Paragraph and Line Location

Reading Passage 3, Daniel Wolpert on planetary colonisation, lines 265–269

Explanation

Wolpert argues that much of Earth remains inaccessible and that robots could gather resources closer to home.

He says this would be a better use of robotic technology.

So, the answer is: B — Daniel Wolpert

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Question 32

Good science fiction may be as accurate as mediocre scientific work.

Keywords

science fiction, science, accurate, wrong

Exact Paragraph and Line Location

Reading Passage 3, Martin Rees on science fiction, lines 312–314

Explanation

Rees recommends high-quality science fiction over poor-quality science because it can be more stimulating and may be no more likely to be wrong.

So, the answer is: A — Martin Rees

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Question 33

Some people welcome robots becoming more intelligent.

Keywords

welcome, robots, machine intelligence

Exact Paragraph and Line Location

Reading Passage 3, Kathleen Richardson on AI risk, lines 308–311

Explanation

Richardson explicitly says not everyone fears robots and that many people welcome machine intelligence.

So, the answer is: C — Kathleen Richardson

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Questions 34–36: Matching Sentence Endings

Strategy

For these questions:

1. Identify the two experts named.
2. Compare their opinions.
3. Find the topic on which they agree or disagree.
4. Select the matching ending.

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Question 34

Richardson and Rees express similar ethical views about ______.

Keywords

Richardson, Rees, ethics, planets

Exact Paragraph and Line Location

Reading Passage 3, Rees lines 259–264 and Richardson lines 270–273

Explanation

Rees argues that colonised planets should be protected rather than heavily transformed.

Richardson also questions the morality of imposing human models on other planets.

Both therefore express ethical concerns about changing planets for human purposes.

So, the answer is: C — changes made to other planets for our own benefit

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Question 35

Rees and Wolpert agree about the extent of ______.

Keywords

Rees, Wolpert, agree, machine intelligence

Exact Paragraph and Line Location

Reading Passage 3, Rees lines 274–280 and Wolpert lines 281–289

Explanation

Both acknowledge that machines already outperform humans in certain limited areas.

However, both also identify important limitations compared with human abilities.

Their shared view concerns how far machine intelligence has progressed so far.

So, the answer is: B — advances made in machine intelligence so far

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Question 36

Wolpert disagrees with Richardson about ______.

Keywords

Wolpert, Richardson, disagree, harm

Exact Paragraph and Line Location

Reading Passage 3, Wolpert lines 303–307 and Richardson lines 308–311

Explanation

Wolpert says artificial intelligence has already caused damage through computer viruses.

Richardson argues that robots have never actually shown themselves to be a threat to humans.

Their disagreement therefore concerns harm already caused by AI.

So, the answer is: D — the harm already done by artificial intelligence

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Questions 37–40: Multiple Choice

Strategy

For multiple-choice questions:

1. Find the relevant speaker.
2. Read the complete response.
3. Summarise the speaker’s central claim.
4. Compare all options.
5. Reject options that contain related words but change the meaning.

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Question 37

What point does Richardson make about fear of machines?

Keywords

Richardson, fear, machines, personify

Exact Paragraph and Line Location

Reading Passage 3, Richardson on machine intelligence, lines 290–296

Explanation

Richardson argues that people tend to personify machines.

Humans create machines in our own image, imagine they think like us and then fear them as autonomous threats.

The fear therefore comes from assigning human-like characteristics to non-human objects.

So, the answer is: B — It results from our tendency to attribute human characteristics to non-human entities.

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Question 38

What potential advance does Rees see as a cause for concern?

Keywords

Rees, concern, computer networks, mind of its own

Exact Paragraph and Line Location

Reading Passage 3, Rees on AI risk, lines 297–302

Explanation

Rees worries that interconnected computer networks could eventually behave like a single brain with a mind and goals of their own.

This is a concern about AI becoming capable of independent thought.

So, the answer is: C — artificial intelligence developing independent thought

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Question 39

What does Wolpert emphasise about science fiction?

Keywords

Wolpert, science fiction, robots, future

Exact Paragraph and Line Location

Reading Passage 3, Wolpert on science fiction, lines 315–318

Explanation

Wolpert says science fiction presents many different possible futures.

However, almost none of them imagine a future without robots.

This emphasises how fundamental robots are to science-fiction visions of the future.

So, the answer is: B — how fundamental robots are to the science fiction genre

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Question 40

What is Richardson doing when discussing reality and fantasy?

Keywords

Richardson, reality, fantasy, divide, perspective

Exact Paragraph and Line Location

Reading Passage 3, final paragraph, lines 321–327

Explanation

Richardson says the division between reality and fiction is not as clear as modern society often assumes.

She argues that different ways of understanding the world sometimes need to be brought together to create a complete perspective.

She is therefore recommending a different way of viewing reality and fantasy.

So, the answer is: C — recommending a change of approach in how people view them

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Cambridge 20 Test 3 Reading Answer Key

Reading Passage 1

1. potatoes
2. butter
3. meat
4. crystals
5. cellophane
6. tin
7. refrigerator
8. NOT GIVEN
9. TRUE
10. FALSE
11. TRUE
12. FALSE
13. NOT GIVEN

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Reading Passage 2

14. v
15. ii
16. iv
17. vii
18. iii
19. vi 20–21. C and E 22–23. B and D
20. tentacles
21. protection
22. colour / color

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Reading Passage 3

27. A — Martin Rees
28. C — Kathleen Richardson
29. B — Daniel Wolpert
30. A — Martin Rees
31. B — Daniel Wolpert
32. A — Martin Rees
33. C — Kathleen Richardson
34. C
35. B
36. D
37. B
38. C
39. B
40. C

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Bonus IELTS Reading Tips

Use Dates as Powerful Keywords

Passage 1 contains several dates:

• 1851
• 1880
• 1917
• 1940s
• 1950s

Dates are easy to scan and often lead directly to the relevant answer.

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Follow the Word Limit

If the instruction says:

ONE WORD ONLY

write only one word.

For example:

• Correct: cellophane
• Incorrect: transparent cellophane

Extra words can make an otherwise correct answer wrong.

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Look for Paraphrases

Question wording	Passage wording
conserved nutritional value	preserved nutritional value
specially adapted trains	insulated rail cars
two kinds of meat	beef and mutton
did not spoil food	reduced damage
product was visible	transparent material
shortage	rationed to save
promotion	advertising
collect food	capturing marine creatures
contamination	pollution
flow of water	ocean current changes
changed sea conditions	warm, acidic waters
speed up reproduction	increase breeding rates
remove colour	strip reefs of colour
restrict abilities	lacking capacity to outwit us
treating robots fairly	guilty about exploiting robots
many decades	next 50 years
more useful on Earth	better use nearer to home

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Understand FALSE vs NOT GIVEN

FALSE

Choose FALSE when the passage provides opposite information.

Example:

> Birdseye travelled to Labrador to study frozen fish.

The passage says he went there to trap and trade furs.

Therefore: FALSE

NOT GIVEN

Choose NOT GIVEN when the passage does not provide enough information.

Example:

> Boston ship owners became very wealthy from the ice trade.

The passage says they transported ice but says nothing about their wealth.

Therefore: NOT GIVEN

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Focus on the Main Idea for Matching Headings

A heading should describe the whole section, not one sentence.

For Section A, the writer discusses both:

• showing visitors the beauty of coral reefs;
• explaining conservation research.

That is why Two clear educational goals is the best heading.

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Be Careful with Matching Experts

Do not match a statement merely because an expert talks about the same general subject.

Focus on the exact opinion.

For example:

• Rees wants robot abilities restricted.
• Wolpert thinks robots may be more useful closer to Earth.
• Richardson thinks humans exaggerate the threat posed by machines.

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Compare Two Experts Carefully

Questions 34–36 require you to compare viewpoints.

Ask:

• Do they agree?
• What exact subject do they agree on?
• Do they disagree about what has already happened or what may happen later?

This prevents you from matching the topic instead of the opinion.

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Watch for Extreme Language

Be careful with words such as:

• largest
• always
• never
• only
• completely
• all
• first

Question 13 says the US industry is the largest in the world.

The passage provides its value but no international comparison.

Therefore: NOT GIVEN

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Read Beyond the First Matching Keyword

Finding a matching word is only the first step.

Read the surrounding sentence because it may contain:

• a contradiction;
• a qualification;
• a correction;
• a limitation.

For Question 12, the important detail is that the aluminium tray was already used by airlines.

That makes the statement FALSE.

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Review Every Incorrect Answer

After completing the test, identify why each mistake happened.

Common causes include:

• missing a paraphrase;
• confusing FALSE with NOT GIVEN;
• ignoring the word limit;
• selecting a heading from one keyword;
• matching the wrong expert;
• overlooking a comparison;
• failing to read enough context.