Question

I don't know if he ________ tomorrow．If he ________, I'll meet him．

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

Answer 1

A
第一个if意为“是否”，引导宾语从句，可用于一般将来时；第二个if意为“如果”，引导条件状语从句，用一般现在时代替将来时。