Ann the lights when you leave the classroom.A. turn onB. turns onC. turns offD. turn off

问题补充：

Ann, the lights when you leave the classroom.

A. turn on

B. turns on

C. turns off

D. turn off

答案：

A. turn on

B. turns on

C. turns off

(答案→)D. turn off

解析：句意：安，当你离开教室的时候关上灯。A. turn on打开； B. turns on打开，动词三单形式；C. turns off关上，动词三单形式；D. turn off关上。本句是祈使句，肯定祈使句以动词原形开头，结合语境，故选D。