请看下面的句子，句子间要用并列连词吗？
If I’m mistaken, _________ you are mistaken too.
A. so B. and C. or D. 不填
空格前 if 引导的是一个条件状语从句，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，you are mistaken too 为主句。又如：
(1) If wishes were horses, _________ beggars would ride.
A. and B. so C. or D. 不填
(2) When the last prize had been awarded _________ everybody cleared off.
A. and B. so C. or D. 不填
(3) Just before I left London, _________ I sent him a telegram.
A. and B. so C. or D. 不填
(4) After they had each said a few words, _________ Lloyd George took the floor.
A. and B. so C. 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，空格后为句子主句。