问题
选择题
None of them knew what had happened _________ I told them about it.
A．when
B．until
C．after
D．though
答案
答案：B
题目分析：when当……时；until直到……才；after在……之后；though虽然，尽管。直到我们告诉他们，他们在知道发生了什么事。短语not……until直到才，本句中none表示否定含义，故选B.