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)