第9题: [单项选择]The alarm clock didn't ring this morning. I ______ it last night. A. did forgotten to wind B. may have forgotten winding C. ought to have forgotten to wind D. must have forgotten to wind 参考答案:D 答案解析:must have forgotten to wind the alarm clock肯定忘记上闹钟了,must have done sth对过去发生事情的推测,肯定已经……,forget to do