Question

Do you know what time it is 还是is it?

Answer 1

　　谓语动词与主语倒装是疑问句语序,所以 Do you know 用了助动词do 提前的倒装语序”,而what time it is 是动词 know 的宾语从句,从句不是疑问句,因此不能倒装.
　　如果把 do you know 用作插入语,那么它就变成了疑问句,需要用 What time doyou know is it 倒装结构.
　　可见,Do you know what time it is?和 What time do you know is it?是两种不同的语法结构.前者Do you know 是疑问句结构的主句,what time it is 是陈述句结构的宾语从句.后者 What time is it 是疑问句结构的主句,do you know 是疑问句结构的插入语.后者的这种结构也叫做双重疑问句,即主句 What time is it 是疑问句结构,插入语 do you know 也是疑问句结构.