概要：1) since +过去一个时间点(如具体的年、月、日期、钟点、1980, last month, half past six)。I have been here since 1989.2) since +一段时间+ agoI 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 +一段时间+ since从句It is two years since I became a postgraduate student.www.51jxk.com为大家整理了一些小升初英语语法讲解知识，希望对同学们有所帮助。

1) since +过去一个时间点　(如具体的年、月、日期、钟点、1980, last month, half past six)。

I have been here since 1989.

2) since +一段时间+ 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 +一段时间+ since从句

It is two years since I became a postgraduate student.

www.51jxk.com为大家整理了一些小升初英语语法讲解知识，希望对同学们有所帮助。