疑问词词组的基本结构是“疑问代词+动词不定式短语”，有一种典型的形式是“疑问代词+ to + 动词原形 ”。疑问词词组可以发挥名词功能，通常被用作宾语。具体示例如下：
I don't know what to say.
Have you decided which to select?
It's always difficult to know when to stop.
Can you teach me how to cook?
They are arguing over who to pay the bill.
No one will tell you where to find gold。
I also don't understand why to buy it.
Many companies faced the question of whether to lay off staff or cut pay.
We are still thinking about which one to choose.
Sarah was not sure whose advice to follow。