---I will go to Guangzhou this summer vacation.---.A. You are welcomeB. Sorry to hear that

问题补充：

---I will go to Guangzhou this summer vacation.

---.

A. You are welcome

B. Sorry to hear that

C. Have a good trip

D. Congratulations

答案：

A. You are welcome

B. Sorry to hear that

(答案→)C. Have a good trip

D. Congratulations

解析：考查交际用语。You are welcome 不用谢，Sorry to hear that听到那个我很伤心，Have a good trip 祝你旅途愉快，Congratulations 祝贺你。句意：今年暑假我将去广州。祝你旅途愉快。故选C。