------Who is the guy with a pair of sunglasses?----He is university student from Island

问题补充：

------Who is the guy with a pair of sunglasses?

----He is university student from Island in England.

A. an; an

B. an; a

C. a; an

D. a; a

答案：

A. an; an

B. an; a

(答案→)C. a; an

D. a; a

解析：不定冠词有a和an两种：a用于辅音音素开头的词前，an用于元音音素开头的词前。