题目内容：

Man has a big brain. He can think and s  1.     languages. Scientists once thought that man isn’t the same as animals b    2.   man can think and learn. They know now that dogs, monkeys and birds can learn, too.

They are beginning to u 3.    that men are different from animals because they can speak. Animals can’t speak. They make much n    4.   when they are afraid, or unhappy. Apes(猿) can learn some things more quickly than man. One or two of them have learned a few words. But they cannot join w  5.  to make sentences. They cannot think l    6. us because they have no language. Language is a wonderful thing. Man has been a   7.   to build a modern world because he has language. Every child can speak his own language very w  8.  when he is four or five, b 9.   no animals learn to speak.

How do children learn it? Scientists don’t really know w    10.  happens inside our body when we speak. They only know that man can speak because he has a brain.