句型转换。

1. He said nothing. (同义句)

    He ________ say ________.

2. He is good at his lessons. (同义句)

    He ________ ________ in his lessons.

3. We have cleaned the blackboard. (变为一般疑问句)

    ________ you ________ the blackboard?

4. He has been a doctor for seven years. (对画线部分提问)

    ________ ________ has he been a doctor?

5. Let's have a rest, ________ ________? (完成反意疑问句)