问题补充：
It’s believed that travelling to Zhenjiang in spring is enjoyable experience.
A. /; the
B. the; an
C. /; an
D. the; the
答案：
A. /; the
B. the; an
(答案→)C. /; an
D. the; the
解析：句意：据信在春天去镇江旅行是一个令人愉快地经历.Spring是专有名词,前面不用冠词.后一空泛指一次愉快的经历,故用不定冠词.enjoyable词首音素是元音,故不定冠词用an,选C.
