Not long ago,an old scientist made some tests with d________ animals to find out which was c________ than other animals.In one test,the old scientist put a monkey in a room where there were many boxes.Some boxes are inside other boxes.One small box had some food in it.The scientist wanted to w________ the monkey and to find out how long it would t_______ the monkey to find the food.The scientist left the room and w_____ a few minutes outside the door.Then he got down on his knees(膝盖) and put his e_______ to the keyhole.What did he see To his s________,he found himself looking into the eye of the m________.The monkey was on the o_________ side of the door and looked at the scientist t_________ the key hole,too.