题干
I only know we will have a League meeting, but I have no idea when _________ it．
A：shall we have
B：will we have
C：to have
D：having
答案(点此获取答案解析）
C
A：shall we have
B：will we have
C：to have
D：having
为偶数）时命题为真，则还需要用归纳假设再证 （ ）