根据短文内容及首字母提示，填写所缺单词 Man has a big brain
问题：
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 1 languages. Scientists once thought that man isn't the same as
animalsb 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 can not join words to make s 5 . They cannot think I 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.
1. _____ 2. _____ 3. _____ 4. _____ 5. _____
6. _____ 7. _____ 8. _____ 9. _____ 10. _____