1)、定義：人稱代詞是用來指代人、動物或事物的代詞。它必須在人稱(第一人稱、第二人稱、及第三人稱)、數（單數、復數）以及性（陰性、陽性、中性）三方面與被指代的名詞一致。
如：I am a student.
Tom is a boy, and he is a student.
Mary is very pretty, and she likes singing.
The boys are students, and they are in the room.
The doy is small. It is Tom's.
2、人稱代詞的句法功能
A) 人稱代詞有主格和賓語之分：主格用作主語，賓格用作賓語。
B) 人稱代詞的主格形式在在句中作主語和表語。
如: I like music(主語).
She is a teacher.(主語)
She and I are good friends(主語).
Neither she nor I am student.
——I saw the boys this morning.
——Are you sure it was they(表語)?
C) 人稱代詞的賓格在句子作動詞的賓語，或者介詞的賓語。
如：I saw him at the party(賓語).
I haven't seen them recently. (賓語)
I bought a book for them. (作介詞賓語)
=I bought them a book. (間接賓語)
【注意】
a. 在口語中，人稱代詞的主格形式作表語時，常常可以用賓格替換。
如：It can't be he/him.
——Is this Mr. Green?
——Yes, this is he/him.
b. 在口語中，當人稱代詞用于than, as 之后或用于強調句中被強調時，用主格(較正式)和賓格(較口語化)均可以。
如：
He sings better than I/me. 他比我唱得好。
You know more than she/her.
She is as tall as me(I am).
c. 單獨使用的人稱代詞通常用賓格，即使它充當的是主語也是如此。如：
“I like English.”
“我喜歡英語。”
“Me too=I like English too.”
“我也喜歡。”