But,they say they will not let the president off the hook until a number of important questions are answered and certain reprehensible acts are ended.

VOA: standard.2009.03.21

This is another thing to notice. He's not just making us experience Lolita's name the way he does; he's assuming that there are certain kinds of questions that we will ask. "Did she have a precursor?"

这也值得注意，他不仅让我们体会,他感知到的Lolita的名字，他想象出了,我们可能会提出的问题，在她之前还有别人吗“

耶鲁公开课 - 1945年后的美国小说课程节选

You use the "who" questions to ask about subjects, to ask who the subject is of the certain action or anything really.

当你要询问主体，即某一行为或事物的主体时，你可以用“who”问句。

Who 课堂 - SpeakingMax英语口语达人