1. —When shall we set about doing our work?
—______ all the group members are here.
A. Until B. Since
C. Unless D. Not until
【答案】D
【解析】
【详解】考查连接词辨析。句意：——我们什么时候开始工作？——直到所有的组员都来了。A. Until在……以前；B. Since自……以来；C. Unless除非；D. Not until直到……才。本句是省略句，完整的句子是We shall not set about doing our work until all the group members are here.由此可知，应使用not until。故选D。
