4.I think it important that Tom come tomorrow. 对important提问是How do you think it that Tom come tomorrow? 还是How do you think that Tom come tomorrow? 假如宾补是其他词性，如何使用疑问词，用how还是what?譬如 He feels it his duty to help others对宾补his duty提问是What does he feel to help others吗？

你的设想不成立。既然对important提问，那样被问者就未必觉得宾语从句表示的内容要紧，从句如何可以用虚拟语气呢？

真的交流中，要对个句子提问就要改变句式。比如：

Do you think it improtant that Tom come tomorrow?

Do you think Tom should come tomorrow?

Whats your opinion about Tom coming tomorrow?

... ...