句型转换。 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 ______ ______.