题目

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：B 解析: 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”。

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