缺词填空   先通读下面的短文，然后根据短文内容和所给首字母，在空格内填入一个适当的单词，使短文意思完整。 所填单词必须在答题卷的横线上完整写出。（本大题共6分， 每空0.5分）
A man once made some tests with d    animals to find out which was the cleverest. He found that the monkey was c    than any o    animal.
In one test, the man put a monkey in a room w   some boxes in it. There was some food in one of the boxes. The man wanted to watch the monkey c  , because he wanted to find out how l   it would take the monkey to get the food. The man c    the door and left the room. He waited for a few m _ outside the door. Then he got d  _ on his knees (膝盖) and put his eye to the keyhole (钥匙孔).What did he s  ? He was surprised to find that he was looking into the e   of the monkey. The monkey was on the o  side of the door and looked through the keyhole.