1. 用所给词的适当形式填空。

1. （1） (not) sleep too late.  It's bad for your health.

3. （2） How many (cup) of yogurt do you need?

5. （3） There's no need (worry) about his study.

7. （4） (turn) off the lights when you leave the room.

9. （5） How many (teacher) are there in your school?