填空

1. He told Tom, "You          ____（不得不）stay after school an extra hour tomorrow."

2. If your teacher_____（送）you to my office again,I'm going to call your mother.

3. They thought,"I don't want my parents          _____（来）to school."

4. Students_____（行为）better because their parents helped them a lot.

5. If you ask the clerks,they            _____（给）you the stamps you need.

一个类可以从直接或间接的祖先中继承所有属性和方法。采用这个方法提高了软件的 【3】 。