--Where did you go on vacation?--I .A. stay at homeB. am going to BeijingC. visit my uncle

问题补充：

--Where did you go on vacation?

--I .

A. stay at home

B. am going to Beijing

C. visit my uncle

D. went to the beach

答案：

A. stay at home

B. am going to Beijing

C. visit my uncle

(答案→)D. went to the beach

解析：句意：你去哪里度假了？我去海滩了。A. stay at home呆在家里，一般现在时；B. am going to Beijing将要去北京，一般将来时；C. visit my uncle拜访我的叔叔，一般现在时；D. went to the beach去海滩了，一般过去时。由上句did可知是一般过去时态，本着时态一致的原则，答语也用一般过去时，故选D。