状语从句易混淆点It was 5 am when we arrived at the village.
2） It was/will be+时间段+before…(没过…就／过了…才)
It was/will be two weeks before we met/meet again
3） It is /has been +时间段+since…（自从…以来有…）
It is/has been 3 years since we last met.
突破点：一看be动词的时态，二看时间段还是时间点。
注意：在“It is /has been +时间段+since…”句型中，从句的动词必须是短暂性的，如果是延续性的动词，时间要从从句的动作结束时算起。
如：
It is 3 years since I smoked.( 偶戒烟有三年了)
补充：as soon as, immediately, directly, instantly, the moment, the minute, the instant, no sooner…than…, hardly/scarcely….when….和once这些从属连接词
引导的从句都表示从句的动作一发生，主句的动作随即就发生，常译为“一…就…”。从句中一般时态代替将来时态。
every time, each time, next time, the first time, any time, all the time等名词短语用来引导时间状语从句，表示“每当…..，每次…..；下次……”等。