这个and是多余的请看下面的题：When the last prize had been awarded _____ everybody cleared off. A. and B. soC. or D. 不填【陷阱】容易想当然地误选A。【分析】句首 when 引导的是一个时间状语从句，它暗示整个句子为复合句；而so, and, or 为并列连词，无论选哪一个，都表明整个句子为并列句，从而导致前后矛盾，所以A、B、C均不能选择。此题正确答案选D，everybody cleared off 为整个复合句的主句。请看类似例子：(1) If wishes were horses, _____ beggars would ride. A. and B. soC. or D. 不填(2) If I’m mistaken, _____ you are mistaken too.A. so B. andC. or D. 不填(3) Just before I left London, _____ I sent him a telegram. A. and B. soC. or D. 不填(4) After they had each said a few words, _____ Lloyd George took the floor. A. and B. soC. or D. 不填答案均选D，空格前分别为 if, when, before, after 引导的状语从句，空格后为整个复合句的主句。

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