问题补充：
—Tomorrow my birthday. I’d like you and Jane to come.
—I’m not sure if she free.
A. will be; is
B. is going to; is
C. is; is
D. is; will be
答案：
A. will be; is
B. is going to; is
C. is; is
D. is; will be
解析：第一空是表示“不以人的意志为转移的客观事实”，用一般现在时；第二空是表示“将来的动作”，用一般将来时。
