1. He likes playing football very much. (改同义句)
    He ______ ______ _______ playing football.
2. It's necessary that we study English well. (改同义句)
    It's necessary _______ _______ ______ study English well.
3. It is possible for fire to cause danger if we are not careful. (改同义句)
    Fire _______ _______ _______ if we are not careful.
4. You mustn't give the goldfish too much food. (改同义句)
    _______ give the goldfish too much food.
5. Fish sleep with their eyes open. (划线部分提问)
    _______ _______ fish sleep?
6. They had a class meeting yesterday afternoon. (改否定句)
    They _______ _______ a class meeting yesterday afternoon.
7. It took the firemen half an hour to put out the fire. (划线部分提问)
     _______ _______ _______ it _______ the firemen to put out the fire.
8. Did he fly to Beijing to visit his friends last week? (改肯定句)
    He _______ _______ Beijing to visit his friends last week.