问题补充：
Sorry，I am too busy now.If I time，I would certainly go for an outing with you.(·湖南)
A. have had
B. had had
C. have
D. had
答案：
A. have had
B. had had
C. have
(答案→)D. had
解析：句意：对不起，我现在太忙了。如果我现在有时间的话，我会和你一起出去郊游。根据句意以及句中的now可知，此处表示对现在情况的一种假设，所以从句中谓语动词要用过去式，而主句用“could/would/should/might＋动词原形”。
