Question

20．直到上周五汤姆才收到他妈妈的来信．
Tomdidn't hear from his mother until last Friday．

Answer 1

分析 didn't hear from his mother until．

解答 答案：didn't hear from his mother until．表达的是过去的事情用一般过去时，表示直到…才，用not…until，收到某人的信用hear from，借助于助动词did构成否定，故答案是didn't hear from his mother 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．