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. Should it not be
网友回答
A. If it is not
B. Were it not
(答案→)C. Had it not been
D. Should it not be
解析：考查虚拟语气：根据主句中的would not have gone 可知，这是与过去事实相反的虚拟语气。结构如下：主句：主语+would/should/could/might+have done+其他
从句：if+主语+had+过去分词+其他，还可以构成倒装：去掉if,把had提前。所以，上面的句子应该是：If it had not been for the free tickets,I would not have gone to the films so often.
写成倒装就是：Had it not been for the free tickets,I would not have gone to the films so often。选C。