as soon as主句和从句的时态

　　as soon as两种用法：

　　1、指未发生的动作，规律是：主句一般将来时，从句用一般现在时代替一般将来时

　　如：I will tell him the news as soon as he comes back。

　　注：有时，为了特意表达刚刚完成某事就如何如何，需要用现在完成时。

　　如：I will go with you as soon as I have washed my face.

　　2、指紧接着发生的两个短动作，主从句都用一般过去时

　　如 He took out his English books as soon as he sat down

　　不过，我也见过从句和主句都用一般现在时的情况。

　　如：As soon as he finishes his classwork, he runs out of the class. 他一做完课堂作业，就跑出了教室。

　　总之，记住那两种基本的情况，不把时态用得太混乱了就行了（比如后面从句里用了将来时，就绝对允许了）。