Relative clauses -000-]]]

當 那個詞在relative clause作object的時候，就要用whom
如：
I'll give my vote to the man in whom I have faith.
我將把我的選票投給我所相信的人。

你可以看作：I have faith in the man(明顯whom在這句裏作object）

She was the girl whom you met at the airport.
她就是你在機場遇見的那個女孩。

you met the girl at the airport（所以可以看到the girl是object，所以也用whom）

we use "Whom" when it is the object of the verb.

eg. THE LITTLE GIRL whom you saw is my sister. (You saw THE LITTLE GIRL (object).)

we use "Who" when it is the subject of the verb.

e.g. I saw the little girl who likes to play with you. ( THE LITTLE GIRL (subject) likes to play with you.)

Traditionally, who is the subjective (nominative) form only. According to traditional Prescriptive grammar: who is a subjective pronoun (subject of the side clause), and whom is the corresponding objective pronoun (an object of the side clause). Whose is the possessive form, not who's which is a contraction. See also: English declension.

He is someone to whom I owe a great deal. ("I" is subject, "whom" (relating to "he") the object)
He is someone who is a great guy. ("who" is subject of the side clause)
He is someone whose help ended my despair. ("whose" is adjunct to help, the side clause's subject)
Whom is falling out of use in informal English (increasingly, especially in American English, in some formal situations as well). In such instances, who has replaced whom as both the subjective and objective form.
Whom remains in significant use following a preposition[citation needed] (see examples immediately below). In informal contexts, the preposition may instead be placed at the end (see preposition stranding), and the word who may be omitted where it is used as a relative pronoun. For example:

(relative, formal): He is someone to whom I owe a great deal.
(interrogative, formal): To whom did you give it?
(relative, informal): He is someone (who) I owe a great deal to.
(interrogative, informal): Who did you give it to?