首先你所给的例子不是宾语从句,而是由before 引导的时间状语从句,宾语从句必须用陈述句语序,而主句没有限制。 can you tell me where you used to live before you came here? he didn't tell me where you used to live, before you came here?
i'm a student you are a teacher tom ** a good boy 否定句 i'm not a student you are not a teacher tom **n't a good boy 疑问句:are you a student?are you a teacher?** tom a good boy?