1.What's the difference between a monkey and a flea(跳蚤)? 2.What is black when it is clean and white when it is dirty? 3.What 5-letter word has six left when you take 2 letters away? 4.What is the center of gravity?
The letter V.
A monkey can have fleas, but a flea can't have monkeys.
A blackboard.
Sixty.
Riddles