Not long ago,an old scientist made some tests with d___ifferent_____ animals to find out which was c____leverer____ 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____atch ____ the monkey and to find out how long it would t___ake____ the monkey to find the food.The scientist left the room and w__atched___ a few minutes outside the door.Then he got down on his knees(膝盖) and put his e___ye___ to the keyhole.What did he see To his s___urpiese_____,he found himself looking into the eye of the m__onkey ______.The monkey was on the o____ther_____ side of the door and looked at the scientist t__hrough______ the key hole,too.