Man has a big brain. He can think and s     languages. Scientists once thought that man isn’t the same as animals b      man can think and learn. They know now that dogs, monkeys and birds can learn, too.
They are beginning to u    that men are different from animals because they can speak. Animals can’t speak. They make much n      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  to make sentences. They cannot think l    us because they have no language. Language is a wonderful thing. Man has been a     to build a modern world because he has language. Every child can speak his own language very w   when he is four or five, b   no animals learn to speak.
How do children learn it? Scientists don’t really know w     happens inside our body when we speak. They only know that man can speak because he has a brain.