—Sorry indeed. I to your birthday party if …
—Forget it. I know you were out on business.
A. must e
B. would e
C. must have e
D. would have e
网友回答
A. must e
B. would e
C. must have e
(答案→)D. would have e
解析：
这题考查虚拟语气的用法，从上下文看，说话人是没能参加生日聚会，所以用would have done，“本可以做却没做”。句意是：--真是抱歉，如果..我本可以去参加你的生日聚会的，--没事，我知道你在外做生意的。选D。