Bats hunt at night because the daytime is already taken, so they need a way to find prey and obstacles without light. The writer runs through an engineer's options: making light costs too much energy, but blind people unknowingly use echoes, the same principle behind wartime sonar. Bats perfected this echolocation millions of years before humans did.
The paragraph matching (1-5) jumps around: A twice, then B, E and D. The summary (6-9) sits entirely in D and follows its order. The sentences (10-13) all come from E, in order.
Answer key and self-check
Type what you wrote and hit mark. Hide the key first if you haven't done the passage yet. Every question number jumps to its explanation.
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Your answer
Answer
Questions 1-5 · Matching information (paragraphs A-E)
How to attack this block: Two answers come from A, so don't cross A off after the first match. A covers why bats chose the night and how early mammals survived the dinosaurs. B is the list of other animals that can't rely on sight. Separate D (the wartime devices) from E (what radar theory has taught us about bats).
Question 1
Answer: BParagraph B
Which paragraph gives examples of other animals that can't use sight to get around?
Deep-sea fish and whales have little or no light by day or by night. Fish and dolphins that live in extremely muddy water cannot see
Question says → Passage says
wildlife other than batsBats are not the only creatures to face this difficulty today
examplesnight-flying insects / Deep-sea fish and whales / Fish and dolphins
do not rely on visioncannot see / conditions where seeing is difficult or impossible
Why: B is a list of animals in the same situation as bats: night insects, deep-sea fish, whales, and fish and dolphins in muddy water. 'Examples' plus 'other than bats' points straight at a list like this.
The trap: Paragraph C mentions fireflies and deep-sea fish too, but there they are making their own light, so they are still using vision.
Question 2
Answer: AParagraph A, second half
Which paragraph explains how early mammals managed to survive?
our mammalian ancestors probably only managed to survive at all because they found ways of scraping a living at night
Question says → Passage says
early mammalsour mammalian ancestors
avoided dying outmanaged to survive at all
Why: A steps back from bats to all mammals: while dinosaurs ruled the day, our ancestors survived by living at night. 'Avoided dying out' is a negative way of saying 'managed to survive'.
The trap: Paragraph E talks about tens of millions of years of evolution in bats, but it's about bats perfecting sonar, not mammals surviving.
Question 3
Answer: AParagraph A, first half
Which paragraph says why bats hunt at night?
the daytime economy is already heavily exploited by other creatures such as birds
Question says → Passage says
why bats hunt in the darknatural selection has favoured bats that make a go of the night-hunting trade
the reasonGiven that there is a living to be made at night, and given that alternative daytime trades are thoroughly occupied
Why: The writer asks why bats don't just hunt by day, then answers: birds and others already fill the daytime, so the night is where bats can make a living. That's the reason the question wants.
The trap: Paragraph B also starts with bats hunting without light, but it describes the problem this creates, not why they hunt at night in the first place.
Question 4
Answer: EParagraph E
Which paragraph shows a discovery that has helped us understand bats?
much of our scientific understanding of the details of what bats are doing has come from applying radar theory to them
Question says → Passage says
how a particular discoveryapplying radar theory
helped our understanding of batsour scientific understanding of the details of what bats are doing
Why: E says the maths behind radar, developed for human machines, is what lets scientists understand bat sonar in detail. That's one discovery feeding our knowledge of bats.
The trap: D is where the radar and sonar devices are described, so people stop there. But D never links them back to bats; that link only comes in E.
Question 5
Answer: DParagraph D, last two sentences
Which paragraph mentions the first military uses of echoes for detection?
it was only a matter of time before weapons designers adapted it for the detection of submarines. Both sides in the Second World War relied heavily on these devices
Question says → Passage says
military usesweapons designers / Both sides in the Second World War
echolocationradio echoes rather than sound echoes
Why: Submarine detection and Second World War devices like Asdic, Sonar and Radar are military uses of echoes. D gives these before the word 'echolocation' is even introduced in E.
The trap: E names the Sonar and Radar pioneers and defines 'echolocation', so it looks like a match. But E doesn't describe any military use.
Summary completion (ONE WORD ONLY)
Questions 6-9
How to attack this block: Everything is in paragraph D, in order: the phantom-limb comparison, what the ears actually pick up, the ship instruments and the wartime use. Each gap needs a single noun or adjective, so copy the passage word exactly and check plural forms.
Question 6
Answer: phantomParagraph D, fifth sentence
What kind of arm or leg is the facial-vision sensation compared to?
the sensation may be referred to the front of the face, like the referred pain in a phantom limb
Question says → Passage says
the way in which painlike the referred pain
arm or leglimb
Why: 'Arm or leg' is the summary's way of saying 'limb', so the gap is the word in front of it. You need an adjective, and 'phantom' is the only one there.
The trap: 'Referred' also sits right before 'pain', and some people write it. But the summary already has 'pain', and the gap describes the arm or leg, not the pain.
Question 7
Answer: echoesParagraph D, middle
Also accepted: obstacles
What do blind people actually pick up through their ears?
The sensation of facial vision, it turns out, really goes in through the ears. Blind people, without even being aware of the fact, are actually using echoes of their own footsteps
Question says → Passage says
actually comes fromreally goes in through the ears
perceivingusing echoes / to sense the presence of obstacles
Why: The ears are the route, and what comes in is echoes of footsteps and other sounds. You need a plural noun after 'perceiving', and 'echoes' is the passage's word. The key also accepts 'obstacles', since sensing obstacles is what the echoes are used for.
The trap: 'Sounds' appears in the same sentence, but the blind person isn't just hearing sounds, they're using the echoes of them. 'Footsteps' is the source of the echoes, not what is perceived.
Question 8
Answer: depthParagraph D, after the blind people
What did the early instruments measure about the seabed?
engineers had already built instruments to exploit the principle, for example to measure the depth of the sea under a ship
Question says → Passage says
even before this was understoodBefore this was discovered
instruments which calculatedinstruments to… measure
the seabedthe sea under a ship
Why: 'Calculated the ___ of the seabed' matches 'measure the depth of the sea'. The gap needs a noun, and 'depth' is it.
Question 9
Answer: submarinesParagraph D, near the end
What were the wartime devices designed to find?
weapons designers adapted it for the detection of submarines
Question says → Passage says
a wartime applicationweapons designers adapted it
devices for findingfor the detection of
Why: 'Finding' is a plain-English version of 'detection'. The thing being detected is submarines. Keep the plural: the summary says 'devices for finding' things in general.
The trap: 'Obstacles' comes earlier in D, but that's what blind people sense, not what the wartime devices were for.
Sentence completion (NO MORE THAN TWO WORDS)
Questions 10-13
How to attack this block: All four sentences come from paragraph E, one after another. Three answers are two-word phrases lifted straight from the text, so the word limit matters. The last one asks for Griffin's job, which the passage gives as a single word before his name.
Question 10
Answer: natural selectionParagraph E, first sentence
What produced the radar-like system in bats long before humans invented radar?
bats, or rather natural selection working on bats, had perfected the system tens of millions of years earlier
Question says → Passage says
Long before the invention of radarThe Sonar and Radar pioneers didn't know it then… tens of millions of years earlier
had resulted in a sophisticated… systemhad perfected the system
Why: The writer corrects himself: it wasn't bats themselves but natural selection working on them that perfected the system. The gap is the subject of the sentence, a two-word noun phrase.
The trap: 'Bats' is the obvious subject, but the sentence already says 'in bats', and the passage deliberately replaces 'bats' with 'natural selection'.
Question 11
Answer: radio wavesParagraph E, second sentence
Also accepted: echoes
Why is 'radar' the wrong word for what bats use?
It is technically incorrect to talk about bat 'radar', since they do not use radio waves.
Question says → Passage says
an inaccurate termtechnically incorrect
are not useddo not use
Why: 'Inaccurate' = 'technically incorrect', and the reason follows 'since': bats don't use radio waves. Radar works with radio, and bats use sound, which makes it sonar. The key also lists 'echoes', but 'radio waves' is the answer the sentence clearly points to.
The trap: 'Sound echoes' is wrong: bats do use sound echoes. Only the radio part is missing from their system.
Question 12
Answer: mathematical theoriesParagraph E, fourth sentence
What do radar and sonar have in common?
But the underlying mathematical theories of radar and sonar are very similar
Question says → Passage says
are based on similarthe underlying… are very similar
Why: 'Based on' is the summary's version of 'underlying'. What underlies both is the mathematical theories, a two-word answer that fits the limit exactly.
The trap: 'Radar theory' appears in the next clause, but that's what scientists applied to bats, not what the two systems share.
Question 13
Answer: zoologistParagraph E, last sentence
What was the job of the person who invented the word 'echolocation'?
The American zoologist Donald Griffin, who was largely responsible for the discovery of sonar in bats, coined the term 'echolocation'
Question says → Passage says
was first used bycoined the term
someone working as aThe American zoologist
Why: 'Coined the term' means invented the word, so this is the right sentence. The gap follows 'a', so you need a singular job noun: zoologist.
The trap: 'American zoologist' fits the word limit, but 'American' is his nationality, not his job. 'Engineer' appears all over the passage, but Griffin isn't one.
Early mammals surviving the dinosaurs by living at night sits in A, which also answers Question 3. Many people assume a letter can't repeat.
Words from this passage worth keeping
nocturnal(A)
active at night
scraping a living(A)
managing to survive with difficulty
obstructed(B)
blocked
prohibitive(C)
so high that it prevents something
uncanny(D)
strange and hard to explain
exploit(D)
make full use of
coined(E)
invented a new word or phrase
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The full Cambridge 7 Test 1 reading paper: all three passages, 60 minutes, marked the second you finish with a review of every answer. Already done it? Take it again and see if the same traps still get you.
Cambridge IELTS 7, Test 1, Reading Passage 1. The passage and questions belong to Cambridge University Press and are not reproduced here. We quote short extracts only as evidence for our own commentary, and the answers are published for self-marking. Get the book for the full text, or sit the test on Langujet.
The rest of Cambridge 7 Test 1
Passage 1 · Questions 1-13 · You're hereLet's Go Bats
