问题补充：
I don’t know if to the party. I will let you know if .
A. he will come; he comes
B. he will come; he will come
C. he comes; he comes
D. he comes; he will come
答案：
(答案→)A. he will come; he comes
B. he will come; he will come
C. he comes; he comes
D. he comes; he will come
解析：句意:我不知道他是否会来参加聚会，如果他来的话，我会告诉你的。第一个空前的if是是否的意思，引导宾语从句，根据句意可知，这里表示将来的事情，故从句中用一般将来时；第二个空前的if是如果的意思，引导条件状语从句，从句中用一般现在时，主句用一般将来时。故选A。
