单选题 Man has a big brain that can think, learn and speak. Scientists once thought that men are different from animals 1 they can not think and learn.
They know now that dogs, monkey and birds can learn, too. They are beginning to understand that men are different from animals because they can speak. Animals can"t speak. They make noises when they are afraid, or angry or unhappy. Apes (类人猿) can understand something 2 than men. One or two of them have learned 3 words. But they can"t join words to make sentences. They can"t think 4 as because they have 5 languages.
Language is a wonderful thing. Man has 6 build a modern world because he uses language. 7 child can speak his own language well when he is four or five, 8 no animal learns to speak. 9 do children learn it? Scientists do not really know. 10 happens inside our body when we speak? They do not know that man can speak because he has a brain.