题目内容：

Pigeons may only have a brain the size of a thimble (顶针), but it appears that pigeons can categorize and name objects in the same way human children learn new words.

A new study from the University of Iowa has shown that the birds are capable of learning to categorize 128 different photographs into 16 basic categories.

Scientists taught three pigeons to sort out different kinds of dogs or types of shoes, for example by using a particular symbol in exchange for a reward. When they were shown black and white pictures of previously unseen dogs or shoes, the birds were able to correctly match these with the corresponding symbols.

The scientists behind the project say this is a similar approach taken by young children when they are first learning words for objects. However, the researchers said it look their birds around 40 days to perfect the task of learning just 16 categories.

Professor Edward Wasserman, who led the work, said: “Our birds’ rate of learning appears to have been quite slow. Would children learn faster than pigeons? Almost certainly. However, our pigeons came to the experiment with no background knowledge at all. Thus, the more relevant comparison group may be newborn babies, who indeed take 6-9 months to learn their first words.”

Writing in the journal Cognition, the researchers said their experiment was a very simple mirror of the way children are taught words — by their parents pointing to pictures and asking them to name the object.

Pigeons are known to be smarter than many birds. Professor Bob McMurray, who also took part in the study, said the results showed that human learning is not as unique as was previously believed.

He said: “Children are facing a huge task of learning thousands of words without a lot of background knowledge to go on. For a long time, people thought that such learning is special to humans. What this research shows is that the ways in which children solve this huge problem may be shared with many species.

1.What’s the main idea of this passage?

A. Pigeons and young children take a similar approach to learn words.

B. Pigeons are known to be smarter than newborn babies.

C. Pigeons recognize objects in the same way children learn words.

D. Pigeons are unique as they can learn like humans.

2.Why does the writer think newborn babies are the more relevant comparison group?

A. They don’t have any background knowledge.

B. They learn relatively slow.

C. Pigeons and newborn babies learn at a similar speed.

D. Young children are smarter.

3.From the passage, we can learn that ________.

A. learning without background knowledge is unique to humans

B. many species may be able to learn without background knowledge

C. pigeons are able to solve many huge problems

D. pigeons are known to be the smartest birds

4.The passage is intended to ________.

A. introduce pigeons    B. prove a fact

C. support an opinion    D. report a study