This is usual way of solving the problem. Can you think of unusual way?A. a; a B. a; anC

问题补充：

This is usual way of solving the problem. Can you think of unusual way?

A. a; a

B. a; an

C. an; an

D. an; a

答案：

A. a; a

(答案→)B. a; an

C. an; an

D. an; a

解析：本题考查的是不定冠词an和a的用法，当第一次提到某物时，要用不定冠词a或an，第一空后接的usual的首个音标为辅音音标，用不定冠词a，而后一空的unusual的首个音标为元音音标，故用不定冠词an，故选答案为B