It is/has……since……的一个问题.

一段时间 +since
表示从这个时间开始到现在---自从~~~以来
用法上It + ( 现在完成时 ) + 一段时间+ since + ( 一般过去时 )
例句：
1. It is / has been four days since I caught a cold. 我感冒已四天了.
2. It is / has been two weeks since we met last. 自从我们上次见面以来已过了两周.
我们会发现“It is +段时间＋since…..句型”在翻译成中文时,有绝然相反的两种意思,一是,“.做...有多长时间了.”另一是“.有多长时间没做...了.”怎样以简洁的讲解让学生明了.我的意思是：先让比较两个句子的意思（中英文对照）.如,
It is five years since he became a soldier.他当兵已经五年了.
It is five years since he was a soldier..他不当兵已经五年了.
再如,
It is two weeks since he fell ill .他病了两星期了.
It is two weeks since he was ill. 他病愈两星期了.
让学生观察since 从句中动词的特点吧.第一种情况的动词是短暂性动词.表示从这点开始.而第二种则是状态性的,可延续的.
练一练：
1. He went abroad in 1997 and has never come back. It is eleven years since he ____the company at home.
A. takes charge ofB. took charge of C. is in charge ofD. was in charge of
**答案选D不选B
2.They asked me to have a drink with them.I said it was nine years since I______a good drink.
A.enjoyedB. was enjoyingC. had enjoyedD. had been enjoying
**答案用 C
3.This is really a splendid evening. It’s years _____I enjoyed myself so much.
A. whenB. thatC beforeD .since
看看这些你就明白了,学英语要结合具体的语境,不要死记语法