Every evening the students go to bed at 10:30 and the lights are turned off.
A. at once
B. on purpose
C. at present
D. as usual
网友回答
A. at once
B. on purpose
C. at present
(答案→)D. as usual
解析：介词短语辨析。A立刻，马上；B故意；C目前，现在；D和平时一样；句意：每天晚上学生都和平时一样在10点30睡觉，灯光就在那个时候被熄灭。故D正确。