全国大众英语测验语法——since的四种用法
1) since +过往一个时候点(如详细的年、月、日期、钟点、1980, last month, half past six)。
I have been here since 1989.
2) since +一段时候+ ago
I have been here since five months ago.
3) since +从句
Great changes have taken place since you left.
Considerable time has elapsed since we have been here.
4) It is +一段时候+ since从句
It is two years since I became a postgraduate student.