He works very hard. Every night he doesn't go to bed ________ el

He works very hard. Every night he doesn't go to bed ________ eleven o'clock.
A、after
B、until
C、since
D、in
【正确答案】：B
【题目解析】：not...until... 直到....才.....句意：他工作非常努力。每天晚上工作到十点他才去睡觉。