题干
______ for the free tickets, I would not have gone to the films often.
A：If it is not
B：Were it not
C：Had it not bee
D：If they were not
答案(点此获取答案解析）
C
A：If it is not
B：Were it not
C：Had it not bee
D：If they were not
、
是两个单位向量，下列四个命题中正确的是