Question

I don't know if he will come．If he ________, please let me know．

1. A.
   will come
2. B.
   come
3. C.
   comes
4. D.
   is coming

Answer 1

C
第一个if引导宾语从句，可以使用一般将来时；第二个if引导条件状语从句，用一般现在时．主句为一般将来时．