问题
选择题
I don’t know whether you happen ____ it, but I’m going to study in the U.S.A. this September.
A. to be heard B. to be hearing C. to hear D. to have heard
答案
答案：D
happen to have done sth 为不定式的完成时, 表示一个已经完成了的动作,强调对于现在的影响.