1. I received a letter from my friend last week. (改为同义句)
    I ______ ______ my friend last week.
2. She is too short to reach the top of the blackboard. (改为同义句)
    She is not _______ _______ to reach the top of the blackboard.
    She is _______short _______ she can't reach the top of the blackboard.
3. Please take this medicine twice a day. (就划线部分提问)
    _______ ______ do I have to take this medicine?
4. Must I finish my homework now? (进行否定回答)
    No, you don't ______ ______.