IELTS Reading sentence completion


In the IELTS reading sentence completion task, you must complete the given sentences using the information in a passage. It is common to come across this question type in the IELTS reading test. These questions are similar to fill-in-the-blank questions which each of us has had experience with in our academic days.

IELTS Reading sentence completion sample task

[Note: This is an extract from a Part 2 task about the evolution of birds and their ancestry.]

The origins of birds

The science of evolutionary relationships has undergone a major change in recent decades. It used
to be the case that all the features of organisms were important in working out their family tree.
But following the work of German entomologist Willi Hennig, many evolutionary scientists now
believe that the only features which carry any useful information are the evolutionary ‘novelties’
shared between organisms. Mice, lizards and fish, for example, all have backbones – so the feature
‘backbone’ tells us nothing about their evolutionary relationship. But the feature ‘four legs’ is
useful because it’s an evolutionary novelty – a characteristic shared only between the lizard and
the mouse. This would suggest that the lizard and mouse are more closely related to each other
than either is to the fish. This revolutionary approach is called cladistics, and it has been central to
the idea that birds evolved from dinosaurs.

The ‘birds are dinosaurs’ theory was first developed by English palaeontologist Thomas Huxley
(1825–1895). According to some accounts, one evening Huxley went to dinner still thinking about
a mystery dinosaur bone in his lab. He knew he was dealing with the lower leg bone (tibia) of a
meat-eating, two-legged dinosaur belonging to the classification known as theropods, but attached
to the tibia was an unidentified extra bone. On the menu that evening was quail, a small bird
similar to a pheasant, and Huxley noticed the same strange bone, attached to the quail tibia on his
plate. He later realised that it was in fact the bird’s anklebone. More importantly, Huxley
concluded that its forms in both dinosaur and bird skeletons were so similar that they must be
closely related.

Huxley’s idea fell out of favour for fifty years following the 1916 publication of The Origin of
Birds by the Danish doctor Gerhard Heilmann. During this time, Heilmann’s theory was widely
accepted. Heilmann had noted that two-legged, meat-eating dinosaurs lacked collarbones. In later
evolutionary stages these bones fuse together to form the distinctive ‘Y’- shaped bone in a bird’s
neck, known as the furcula. Heilmann proposed the notion that such a feature could not be lost and
then re-evolve at a later date, so dinosaurs could not be the ancestors of birds.

Then, in the late 1960s, John Ostrom from Yale University in the US, noted 22 features in the
skeletons of meat-eating dinosaurs that were also found in birds and nowhere else. This reset the
thinking on bird ancestry and once again Huxley’s ideas caught the attention of the scientific
community. Subsequent work has found up to 85 characteristics that tie dinosaurs and birds
together. But what of Heilmann’s missing bones? It turns out that not only did many dinosaurs
have collarbones, these were also fused together into a furcula. Unfortunately for Heilmann, the
fossil evidence was somewhat lacking in his day, and the few furculae that had been found were
misidentified, usually as belly ribs

US ornithologist Alan Feduccia and palaeontologist Larry Martin are two vocal opponents of the
dinosaur theory. They contend that birds evolved from some unknown reptile at a time long before
dinosaurs. Their reasoning is that flight is most likely to have started from a tree-climbing
ancestor, yet all the proposed dinosaurian ancestors were ground-dwellers. But the dino-bird
supporters contend that an unknown dinosaurian bird-ancestor could have been tree-dwelling, or
that birds evolved flight from the ground up by chasing and leaping after insects. Most of
Feduccia and Martin’s case against the ‘birds-are-dinosaurs’ hypothesis is based on differences
between birds and dinosaurs. Supporters of cladistics, however, maintain that differences between
organisms do not matter, as it is the similarities between them that count. Evolution dictates that
organisms will change through time, so it is only the features which persist that carry useful
information about their origins.

Most people on either side of the debate do accept, however, that the ancient winged creature
known as Archaeopteryx is an ancestor of today’s birds. This is in spite of the fact that its form is
distinctly non-bird-like, with a long bony tail, and teeth instead of a beak. The ‘birds-aredinosaurs’ supporters contend that, if clearly-preserved feathers had not been found alongside two
of the seven Archaeopteryx specimens, it would probably have been identified as a small dinosaur.
However, Archaeopteryx does have some bird-like features, such as a furcula and bird-like feet,
that suggest that it is too bird-like to be considered a dinosaur.

Over the last few decades several dinosaurs with bird-like features and primitive birds with
dinosaur-like features have been found in several countries, connecting Archaeopteryx back to
dinosaurs, and forwards to modern birds. Sinosauropteryx, excavated from 130-million-year-old
rocks in northeast China, is one example. It is a dinosaur skeleton surrounded by a halo of fuzz,
thought to be primitive feathers. And a reassessment of other dinosaurs reveals such bird-like
features as hollow bones and a foot with three functional toes, characteristics that appeared over
50 million years before Archaeopteryx took to the air. And Rahonavis, a primitive bird from
Madagascar is more bird-like than Archaeopteryx, yet retains some distinctive dinosaur features,
including a long and vicious claw at the end of its wing. Over a century since Huxley’s discovery,
it seems that cladistics may have finally settled the ‘dino-bird’ debate

Source: Official IELTS website www.

IELTS reading sentence completion

Source: Official IELTS website www.

IELTS Reading sentence completion tips

Expect 4 – 5 sentences with gaps

You can get 4 to 5 sentences that you will need to complete for the IELTS reading sentence completion task.

Answers will appear in the same order as the sentences

The answers needed to complete the sentences will appear in the same sequence as the sentences. This means that the answer to the first sentence will appear before the answer to the second sentence in the given text.

Search for synonyms of the keywords

Avoid searching for exact keywords. It is better to look for synonyms of the keywords.

Avoid grammatical mistakes

When completing the sentences ensure that the sentences are grammatically correct. Only correct answers will be grammatically correct.

IELTS Reading sentence completion strategy

Read the question

Read the question carefully to see how many words are needed to answer the question. In the example above, you must select one word only from the given passage.

Read the sentences

After you have read and understood the question read the sentences. Try to understand their meaning.

Identify the keywords

Identify the relevant keywords in the sentences. These keywords will help you identify the information you will be searching for in the given text. Avoid searching keywords in the given text instead focus on their meaning and search for synonyms of the keywords.

Skim the text

Skim the given text and search for the identified keywords. Start with the first sentence and attempt the sentences in the same sequence as they appear. The answers will appear in the same order in the text as the sentences. So it is not recommended to skip the sentence sequence and attempt them out of order.

Read the text

Once you have located the keyword in the text, read the text in detail and understand its meaning. This will help in identifying the answer.

Check the answer

Once you have found the answer and completed the sentence, ensure to check the sentence for grammatical errors. Only the correct answer will ensure a grammatically correct sentence. if the final sentence is not grammatically correct the answer you selected is probably incorrect.

Correct answers

  1. Theropods
  2. Collarbones
  3. reptile
  4. similarities
  5. claw

Work out the answers

I first read the question to identify that each sentence could be filled with one word only. Then I read the sentences and identified the keywords I needed to search in the text.

1 Huxley formulated his theory while studying a dinosaur belonging to a group called …………

I skimmed the first paragraph looking for Huxley but couldn’t find it. Then I started skimming the second paragraph where I came across the first keyword Huxley. It is evident that Huxley first developed the theory birds are dinosaurs. Notice how developed is used as a synonym in the place of formulated.

In the last line, the word group doesn’t appear instead its synonym classification is used. This is why it is important to focus on the meaning rather than a word-to-word match.

I then summed up that Huxley formulated his story while he was working on the bone of a dinosaur which belonged to a classification or group called theropods.

Then I tried to fit the word theropods into the sentence and found that it made grammatical sense. Theoropods is the correct answer.

2. Heilmann rejected Huxley’s theory because of the apparent absence of…………… dinosaurs.

I started skimming for the key-word Heilmaan from the third paragraph as the first two paragraphs I had already covered in the first question. I was also looking for what was the missing or absent feature due to which Heilmann had rejected the theory. Note that fell out of favour is used as a synonym for rejected and lacked is used as a synonym for absence of. In the third paragraph, it is mentioned that he had noted that the two-legged, meat-eating dinosaurs lacked collarbones. Collarbones is the correct answer.

3. Feduccia and Martin believe that the ancestor of today’s birds was a kind of early …………

I skimmed the fourth paragraph for Feduccia and Martin but couldn’t find it so, I moved to the fifth paragraph, where they appear in the first sentence. then I read the text looking for who they believed was the ancestor of today’s birds. Note how evolved is used as a synonym for ancestor in the text. It is mentioned that they believed that the birds evolved from some unknown reptile. recall how the question instructions mention to use only one word so the correct answer would be reptile.

4. In cladistics, the …………… between organisms’ characteristics are of major importance.

I continued skimming and searching for cladistics in the fourth paragraph. note how that count is used as a synonym for major importance. It is mentioned that the differences between the organisms don’t matter and the similarities between them count. Similarities is the correct answer.

5. The dangerous…………….on a primitive bird from Madagascar adds weight to the ‘dino-bird’ argument.

I started skimming and searching for a primitive bird of Madagaskar and came across it in the sixth and last paragraph. Then I started to look for the feature of the bird that was dangerous. Note how vicious has been used as a synonym for dangerous in the text. Claw is the correct answer as it’s the dangerous feature at the end of Rahonavis

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