句型转换。

1. John answered all the questions. (改为被动语态)

    All the questions _____          _ _____ John.

2. They are too tired to continue working. (改为同义句)

    They are _____ _____ _____  they can't continue working.

3. His brother joined the army when he was 22. (改为同义句)

    His brother joined the army _____ _____ _____ _____ 22.

4. What a tall tree this is! (用how改写)

    _____ _____ _____ tree this is!

5. Some people believe that Chinese is difficult to learn. (改为同义句)

    It _____ _____ _____ Chinese is difficult to learn.