Some naughty boys like to play trick on their classmates on April Fool’s Day.A. aB. anC.

问题补充：

Some naughty boys like to play trick on their classmates on April Fool’s Day.

A. a

B. an

C. the

D. /

答案：

(答案→)A. a

B. an

C. the

D. /

解析：句意：有些淘气的男孩喜欢在在四月愚人节那天开他们的同学的玩笑。根据题干意思考的是一个固定词组，即：play a trick on sb与某人开一个玩笑，所以选A。