Question

Brain twister.（脑筋急转弯）

1. When do dogs have eight legs?
_______________________________________________
2. What is black when it's clean but white when it's dirty?
_______________________________________________
3. What letter is an anima ?
_______________________________________________
4. What letter is a question?
_______________________________________________

Answer 1

1. When there are two dogs.
2. A blackboard.
3. Letter B (bee).  
4. Letter Y (why).
答案不唯一