do you think在句中是什么成分?他改变句序吗?what do you think you are doing?---我觉得这句改变了which do you think best summerize the author's purpose?--这句又没改变

都没改变啊，都做插入语
what（ do you think ）you are doing?
which （do you think best） summerize the author's purpose?
第一个句子what是doing的宾语
第二个句子which是主语，summarize是宾语

do u think是你怎么认为，怎么想的意思
没有完全弄清楚楼主的意思，但是第二局不通
应该是 which do u think is the best that summerize the authors purpose
*前必须要有the ，这是肯定的
do u think是不改变句序的（问题的句序），问题的句序是普通的陈述句的句序是不一样的

首先 do you think 之类的插入语,不会改变整体意思,是询问对方意见的用法.第一句分析：what are you doing?-> what do you think you are doing?这时候因为插入了 do you think,原来的are you doing 变成了think的宾...

这里do you think 是插入语，当他插到一个特殊疑问句中是， 要位于主语和谓语之间。 但是， 后面特殊疑问句就按宾语从句的语序了。
eg:
What are you doing? 加入了插入语后就成了：
What do you think you are dong?