時間狀語從句，條件句中，從句用一般現在時代替將來時

When, while, before, after, till, once, as soon as, so long as, by the time, if, in case (that), unless, even if, whether, the moment, the minute, the day, the year, immediately

He is going to visit her aunt the day he arrives in Beijing. 他一到北京，就去看他姨媽。

典型例題

(1)He said he________me a present unless I_______ in doing the experiment.

A. had not given; had not succeeded　　B. would not give; succeed

C. will not give; succeed　　　　　　 D. would not give; will succeed.

答案B. 在時間，條件或讓步主語從句中一般不用將來時。本題有He said，故為過去式。主句用將來時，故選B. 此處用一般過去式代替了過去將來時。

(2) 表示現在已安排好的未來事項，行程等活動。

The museum opens at ten tomorrow.　博物館明天10點開門。(實際上每天如此。)