听力题 Man has a big brain. He can think, learn and speak. Scientists once thought that men are different from animals because they can think and learn. They know now that animals can learn — dogs, rats, birds can learn. So scientists are beginning to understand that men are different from animals because they can speak. Animals can not speak. They make noises when they are afraid, or angry, or unhappy. Apes can understand some things more quickly than humans, one or two have learned a few words. But they are still different from us. They can''t join words and make sentences. They can not think like us because they have no language. They can never think about the past or the future. Language is a wonderful thing. Man has been able to build a modern world because he has language. Every child can speak his own language very well when he is four or five — but no animal learns to speak. How do children learn? What happens when we speak? Scientists do not really know. They only know that man can speak because he has a big brain.