关于since和beforeIt was two years

网友回答

答案：D句意：过了两年后他就回国了.
解析：考查句型： It was + 一段时间+ before 过了多久就……
例：It wasn’t two years before he left the country. 还没到两年他们就 离开了那国家.
It was a long time before I fell asleep last night.
昨晚过了很久我才入睡
注意区分since,that,when与before的用法!
It was (not ) + 时间段+before + 一般过去时 过了一段时间就……..
It will (not )be+ 时间段+before + 一般现在时 要过一段时间才会…
It is/ has been +时间段+ since…..
It was +点时间+ when…..
It was +时间状语+ that …..（强调句）
1). It was not long before he sensed the danger of the position.不久他就意识到他处境危险（动作已发生）
2). It will be half a year before you graduate from the school. 还有半年你才从这个学校毕业（动作未发生）
3). It is 3 years since he worked here.=he left here.（since从句中的谓语动词若是延续性动词,要从这个动作结束的时候算起）
4). It was 3 o’clock when they received the telephone.
5) It was at 3 o’clock that they received the telephone.