问题补充:
Ann, the lights when you leave the classroom.
A. turn on
B. turns on
C. turn off
D. turns off
答案:
A. turn on
B. turns on
(答案→)C. turn off
D. turns off
解析:句意: Ann,当你离开教室的时候关上灯。turn on 打开(电视、电脑等);turn off 关上,是turn on 的反义词。这里根据句意应是离开教室要关灯,故应用turn off。并且该句是一个祈使句,所以应用动词原形。故选C。