1. They are happy to see each other. (改为感叹句)
    ______ ______ they are to see each other!
2. The exam begins at nine. (改为一般疑问句)
    ______ the exam ______ at nine?
3. He was playing basketball at four yesterday afternoon. (就划线部分提问) 
    What ______ he ______ at four yesterday afternoon?
4. He had nothing for breakfast. (改为反意疑问句)
    He had nothing for breakfast ______ ______?
5. She doesn't think I can surf on the Internet. (改为反意疑问句)
    She doesn't think I can surf on the Internet, ______ ______?
6. He's put the tree in the hole? (改为一般疑问句)
    ______ he ______ the tree in the hole?
7. How useful the book is! (改为陈述句)
    It is ______ ______ useful book.
8. The population of Australia is about 19,500,000. (就划线部分提问)
     ______ ______ population of Australia?
9. The meeting will start in ten minutes. (就划线部分提问)
     ______ ______ will the meeting start?
10. Don't tell him to come to my office. (改为肯定的祈使句)
      ______ ______ to come to my office.