Which of these do you think is the most useful invention?中do you think 为什么不能换为you think

问题描述:

Which of these do you think is the most useful invention?中do you think 为什么不能换为you think
do you think 为什么不能换为you think?you think 是陈述语序,前面已有which of these做疑问,为什么还要用do you think呢?
请再举一些例子说明

do you think 是插入语,后面的句子要用陈述语语序,即which of these 是主语,is the most useful invention 是系表结构作谓语,又如
When do you think he will come tomorrow 我想问的是为什么do you think不用you think