This is very simple but it's a great way to ask about a specific category among many different categories.

这是个非常简单的句型，但它在询问不同种类中某一特定类型的事物时是非常理想的句型。

What kind of 课堂 - SpeakingMax英语口语达人

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

or you can turn it into a question, and ask "Is there" to ask the existence of something.

当然你也可以把它变成一个问句，用“Is there”来询问某些事物是否存在。

There is 课堂 - SpeakingMax英语口语达人