[外语] 请教一句英语句子的语法

What does Jeff  think is a great idea? 中文翻译：Jeff认为什么是好主意？
这句句子的主句是What does Jeff think? 还是 What is a great idea?
我怎么觉得不管主句是哪一句，整个句子的语法都解释不通，或是句子本身有错？.

主句是What is a great idea?   "does Jeff think"是插入语.

原来如此，很有道理。印象中插入语常用逗号或破折号分开，再特意去查了一下语法书，确实也有不用隔开直接插入句子中的。例句如下：
How long did she say she would stay here?
What do you think we should do after work?

但是，还有不明白的，上面两句例句，主句是 How long she would stay here?  What we should do after work? 那不成疑问句啊？

还是1楼的句子 What does Jeff think is a great idea? 的主句 What is a great idea? 这可是正常的疑问句啊？

还盼指教。谢谢！

[ 本帖最后由 leileima 于 2007-11-28 15:02 编辑 ].