问题补充:
I don’t know when he . But if he , I’ll ring you up.
A. comes, will come
B. will come, will come
C. comes, comes
D. will come, comes
答案:
A. comes, will come
B. will come, will come
C. comes, comes
(答案→)D. will come, comes
解析:本题考查动词时态。第一个空前的when引导宾语从句,此处用一般将来时;第二个空前的if作“如果”讲,引导条件状语从句,主句用了一般将来时,故此处用一般现在时表示将来。