1. It be +时间段+before...过了多长时间才。。。。。。:
It was two days before he knew.过了两天他才知道。
It was three years before he came back from abroad. 过了三年他才从国外回来。
2. It be+ 时间点 +when... 当。。。。。。时候,时间是。。。。。。:
It was six when he arrived.当他到达时,时间是6点钟。
3. It is / has been +时间段 +since...(往往用非延续性动词)自从……以来到现在已有多久,
做。。。。。。已经多长时间了:
It is / has been five years since he died. 他已经死了5年了。
4. It is three years since they got married.他们已经结婚三年了。
It is three years since they were married. 他们已经离婚三年了。(若since引导的
状语从句的谓语动词是持续性动词或表示状态动词的过去时时,则从句表示的时间是“从动作或状态结束时算起”。)再如:
It has been quite some time since I was last in London.我上次离开伦敦至今颇有一段时间了。
5. It won't be long before...:不久。。。。。。
It won't be long before we meet again. 我们不久会再见面。