问题补充：
We the difficulty together, but why didn you tell me?
A. should face
B. might face
C. could have faced
D. must have faced
答案：
A. should face
B. might face
(答案→)C. could have faced
D. must have faced
解析：考察情态动词。本题可采取排除法做题，but之后内容为过去时，因此前面空格部分所写内容应与过去相关，排除A、B两个选项。而D项表示对过去事实的肯定推测，与didn you tell me不符。could have done表示过去本能做的事情却没有做。句意：我们本能一起面对困难的，你（那时）为什么不告诉我？
