Question

17．她直到妈妈回来才停止弹琴．
?Shedidn't stop playing the piano until her mother came back．

Answer 1

分析 didn't stop playing the piano until．

解答 答案：didn't stop playing the piano until．这里是说过去的事情用一般过去时，表示直到…才…用not…until…，表示停止正在做的事情用stop doing sth，stop是实意动词，借助于助动词did加上not，故didn't stop，弹钢琴play the piano，故答案是didn't stop playing the piano until．

点评 not…until指的是"直到…才"的意思，如 I did not go home until my mother called me．
我直到我妈妈打电话给我才回家．
当Not until位于句首时，句子要倒装．其结构为：Not until+从句/表时间的词+助动词+（主句）主语+谓语+．如：
①Not until the teacher came in did the students stop talking．直到老师进来学生们才停止讲话．
②Not until next week will the sports meet be held．直到下周才开运动会．