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。