【典型例题】
[例1] You will be late ___ you leave immediately.
A. unless B. until C. if D. or
答案：A
解析：句意：除非你立即走，否则你就会迟到的。可转化为 If you dong leave immediately, you will be late。B、D句意不对，or表转折，句子如为 You leave immediately or you will be late.
[例2] ____ it with me and I’ll see what I can do.
A. When left B. Leaving C. If you leave D. Leave
答案：D
解析：该题考查祈使句与状语之间的差别。and是连词，应该连两个语法作用相同的句子，而不能连接一个主句一个从句。
