题目内容：

A man once made some tests with .d1.animals to find out which was the .c2.. He found that the monkey was cleverer than any other animal.

In one test, the man put a monkey in a room w3.some boxes in it. There was some food in one of the boxes. The man wanted to watch the monkey closely, because he wanted to find out how .l4. it would take the monkey to get the food. The man .c5. the door and left the room. He waited for a few .m6. outside the door. Then he got down on his knees(膝盖) and put his eye to the keyhole(锁孔). What did he see? He was .s7.to find that he was looking into the e8. of the monkey. The monkey was on the o9. side of the door and looked t10.the keyhole.