问题补充：
Frank to see his grandma if he free tomorrow.
A. will come ; will be
B. comes ; is
C. will come ; is
D. is; come
答案：
A. will come ; will be
B. comes ; is
(答案→)C. will come ; is
D. is; come
解析： if引导的条件状语从句遇到将来通常用一般现在时来表示，故本题后空应用is，本题的含义是如果明天他有空，他将来看奶奶，主句表示将来，要用将来，用will加动词原形，故选C。
