Which question word to use?
该用哪个疑问代词?

We use who to ask questions about people:
我们用who问关于人的问题:

Who is that?

Who lives here?

Who did you see?

We use whose to ask about possession:
我们用whose问关于所有权的问题:

Whose coat is this? [or] Whose is this coat?

Whose book is that? [or] Whose is that book?

Whose bags are those? [or] Whose are those bags?

We use what to ask questions about things:
我们用what问关于事物的问题:

What is that?

What do you want?

We use which to ask someone to choose something:
我们用which问某人选择某物的问题:

Which came first, the chicken or the egg?

I’ve got two books. Which do you want?

We can also use what and which with nouns:
我们也可以用what和which接名词:

What subjects did you study at school?

What newspaper do you read?

Which newspaper do you read – the Times or the Guardian?

Which book do you want?

Which one is yours?

Questions with prepositions:
疑问代词加介词:

Questions ending in prepositions are very common in English. After Who, Which or What we often have a preposition at the end of the sentence:
以介词结尾的疑问句在英语中很普遍。在Who, Which or What后面我们经常以一个介词来结尾:

Who does this book belong to?

What are you looking for?

Which university did you go to?

What country do you come from?