说明

先行词是地点用 where、时间用 when、reason 用 why，它们在从句中作状语；若从句缺主语或宾语，则要用 which / that。

同类条目

• 主谓一致：就近原则 —— Either you or he is right.
• 现在完成时 vs 一般过去时 —— I have lived here for 5 years. / I lived there in 2010.
• 定语从句：that 与 which —— The book that/which I bought is good.
• 虚拟语气：if 条件句 —— If I were you, I would take it.
• 非谓语：doing 与 to do —— I enjoy reading. / I want to go.
• 倒装：否定词提前 —— Never have I seen such a thing.
• 比较级：as ... as 与 than —— He is as tall as I am. / He is taller than I am.
• 情态动词表推测 —— It must be true. / It can't be true.