for the free tickets, I would not have gone to the films so often.
A. If it is not
B. Were it not
C. Had it not been
D. If they were not
网友回答
A. If it is not
B. Were it not
(答案→)C. Had it not been
D. If they were not
解析：句意：要不是免费的票，我不会这么经常去看电影。从主句中would not have gone可以看出是与过去相反，故从句应该使用had done. C答案省略了if，提前had，相当于if it had not been. 故选择C。