句型l：There was a time when．．．曾经有段时间……

There was a time when I played truant from time to time．  曾经有段时间我不时地逃学。

There was a time when Tom failed in some of the exams at  school．曾经有段时间汤姆有些学科考试不及格。

句型2：happen to do…when…当……的时候,碰巧……

Mary’s husband happened to fall ill when she set out．    玛丽出发时碰巧丈夫病了。

The old lady happened to hang about at the station when her family were looking for her everywhere．当家人在到处寻找老太太时,她碰巧在车站闲荡。

句型3：not…until直到……才……

She didn’t enter my room until I returned．

直到我回来时,她才进我的房间。

It was not until he took off his dark glasses that I recognized  him．直到他摘掉墨镜我才认出他。