问题
选择题
The meeting was expected to start at 9 o'clock but the manager didn't turn up ______ twenty minutes later.
A．before
B．until
C．after
D．since
答案
答案：B
本句含到了时间状语从句，也可以看成是not…until…结构，意为“直到…才…”。句意为“直到20分钟后经理才出现”。