如何分析這個疑問句

有這樣一道題：

What do you imagine _________ him from going?

A. to prevent           B. preventing           C. to have prevented  D. prevented

此題答案選D，其中的 do you imagine 為插入成分，如果去掉的話，顯然prevented為句子的謂語。以下各例中的 do you think (suppose, imagine, guess, etc) 也是插入成分，其后接的句子應(yīng)用陳述句詞序：

Who do you think he will marry? 你認(rèn)為他會同誰結(jié)婚？

What do you think we should give her? 你認(rèn)為我們該給她點(diǎn)什么呢？

When do you believe he will come? 你認(rèn)為他會什么時候來？

What do you guess he wants to buy? 你猜他想買什么呢？