根据短文内容及首字母提示，填写所缺单词.
Man has a big brain. He can think and s 小题1: languages. Scientists once thought that man isn’t the same as animals b 小题2: man can think and learn. They know now that dogs, monkeys and birds can learn, too.
They are beginning to u 小题3: that men are different from animals because they can speak. Animals can’t speak. They make much n 小题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 小题5: to make sentences. They cannot think l 小题6: us because they have no language. Language is a wonderful thing. Man has been a 小题7: to build a modern world because he has language. Every child can speak his own language very w 小题8: when he is four or five, b 小题9: no animals learn to speak.
How do children learn it? Scientists don’t really know w 小题10: happens inside our body when we speak. They only know that man can speak because he has a brain.
