词后，也可以用who.

　　To whom do you usually turn when in trouble?

　　Whom/who do you usually turn to when in trouble?

　　当你处于困境时，通常向谁求助?

　　2.whose

　　whose表示“谁的”，即可置于名词前，作定语，也可单独使用。在句中，可作主语，宾语，表语和定语。

　　They are all good at maths,but whose is the best?

　　他们都擅长数学，但谁的最好?(作主语)

　　Whose do you like better, Jack’s or Sally’s?

　　你更喜欢谁的呢，杰克的还是纱丽的?(做宾语)

　　Both Jim and Jack speak English. Whose pronunciation is better?

　　吉姆和杰克都说英语，谁的发音更好呢?(作定语)

　　Heven has already taken her bag away. Whose is this?

　　海伦已经把她的书包拿走了，这是谁的呢?(作表语)

　　whose既可指单数，也可指复数。

　　Whose is this album of stamps of 2003?

　　= Whose album of stamps of 2003 is this?

　　这本2003年集邮册是谁的?

　　Whose are those packages of cookies?

　　=Whose packages of cookies are those?

　　这几包甜饼是谁的?

　　3.which

　　which意为“哪一个，哪一些”，既可指人也可指物，既可指名词的单数，也可指复数。在句中作主语，宾语，定语等。

　　Which is more interesting,this book or that one?

　　这两本书哪一本更有趣?(作主语)

　　I don’t know which to choose.