问题补充：
-- Why didn’t you go to Mike’s birthday party yesterday?
-- Well, I , but I forgot it.
A. should
B. would
C. should have
D. must have
答案：
A. should
B. would
(答案→)C. should have
D. must have
解析：这是一组对话。上文，昨天，你为什么没去参加Mike的生日聚会？下文，我本应该去的，但是我忘记了。Should have done本该做某事，而实际上没有做某事。
