as soon as从句用完成时和过去式的区别

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【AS SOON AS...】

当主句是一般将来时时,as soon as引导的状语从句应用一般现在时
I wil tell him the news as soon as he comes back．
他一回来我就会告诉他这个消息,其实他回来也是将来发生的,也应该用将来式,用现在式是时态简化的原因
As soon as the sun  set we returned to our hotel.
The baby smiled at his mother as soon as he saw her.

表示过去时,主句从句全用过去式,因为几乎是同时发生的

用过去完成式是在hardly..when,no sooner..than中
as soon as,
hardly…when…
no sooner…than…
这三个短语都有“一……就”、“刚刚……就”的意思,它们的意思非常相近,因此有时可以互换.例如：“我刚到公共汽车站,汽车就开了.”一句,就可以有如下几句译法：
As soon as I got to the bus stop,the bus started.
Hardly had I got to the bus stop when the bus started.
No sooner had I got to the bus stop than the bus started.