Rememberoff the lights when you leave the classroom.A. turnB. to turnC. turningD. turned

问题补充：

Rememberoff the lights when you leave the classroom.

A. turn

B. to turn

C. turning

D. turned

答案：

A. turn

(答案→)B. to turn

C. turning

D. turned

解析：句意：当你离开教室时，记得关掉电灯。Remember后接不定式表示记得去做某事，接动名词表示记得做过某事，结合语境可知选B。