在现在完成时的句子中,since后面接过去的某一具体时间点，以下是精品学习网整理的since的四种用法讲解，请考生学习。

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.

2016年高中英语二轮复习since的四种用法讲解分享到这里，更多内容请关注海南高考英语栏目。

相关链接

2015-2016高考第二轮备考英语作文句法结构错误总结 

专家解读2016年高考英语命题方向预测