as soon as 的用法一般是兩種情況：
1、指未發(fā)生的動作,規(guī)律是：主句一般將來時(shí),從句用一般現(xiàn)在時(shí)代替一般將來時(shí)
如：I will tell him the news as soon as he comes back.
注：有時(shí),為了特意表達(dá)剛剛完成某事就如何如何,需要用現(xiàn)在完成時(shí).
如：I will go with you as soon as I have washed my face.
2、指緊接著發(fā)生的兩個(gè)短動作,主從句都用一般過去時(shí)
如 He took out his English books as soon as he sat down
不過,我也見過從句和主句都用一般現(xiàn)在時(shí)的情況.
如：As soon as he finishes his classwork,he runs out of the class.他一做完課堂作業(yè),就跑出了教室.
總之,記住那兩種基本的情況,不把時(shí)態(tài)用得太混亂了就行了（比如后面從句里用了將來時(shí),就絕對允許了）.