you turn off all the lights when you leave the classroomA. Making sureB. To make sureC.

问题补充：

you turn off all the lights when you leave the classroom．

A. Making sure

B. To make sure

C. Being sure

D. Make sure

答案：

A. Making sure

B. To make sure

C. Being sure

(答案→)D. Make sure

解析：考查祈使句：句意是：当你离开教室时要把所有的灯都关了。根据句式判断应该用祈使句。选D。