问题补充：
---I argued with my best friend . what advice do you have for me?
---Well, you say you are sorry, although it’s not easy.
A. will
B. might
C. should
D. must
答案：
A. will
B. might
(答案→)C. should
D. must
解析：考察情态动词。will将要；might 可能；should应该； must 必须。句意：我和我最好的朋友吵架了。你对我有什么建议？——哦，你应该说你很抱歉，尽管那不太容易。
根据提问的内容，可知给出建议，用should do sth，表示应该做某事。故选、C
