---Sorry I can’t go camping with you. I have to prepare well enough for the entrance

问题补充：

------ Sorry, I can’t go camping with you. I have to prepare well enough for the entrance exam.

------! We can camp together next time.

A. Don’t say so

B. My pleasure

C. No problem

D. Unless

答案：

A. Don’t say so

B. My pleasure

(答案→)C. No problem

D. Unless

解析：考查交际用语。A为错误表达。B别客气；C没问题；D除非。句意：——对不起，我不能和你一起去野营。我不得不充分准备好入学考试。——没问题！下次我们可以一起野营。故C正确。