英語中的人稱代詞(Personal Pronouns)有主格、賓格和所有格之 分，如：
I, me, my ; he, him, his ; they, them,their等。
顧名思義，主格(The nominative case)用作主語，賓格(The objective case)用作賓語，所有格(The possessive case)則表示所有之物。
在實際運用中，主格和賓格代詞有時會混淆。下面是常見的問題：
⒈在複合結構裏，人稱代詞的主格和賓格在單獨使用時，沒有問題，如很少人會犯下這樣的.錯誤：
(1)Wilcox spoke to I.
(2)Her knew what had happened.
但在複合結構中，錯誤就難免了，如：
(3)Wilcox spoke to my friend and I.
(4)He and her knew what had happened.
(5)This is between you and he.
這種錯誤是可避免的。第一，在有介詞的複合結構中，特別要注意，第二個人稱代詞，必須用賓語，如："for you and me"和 "between Maria and him".第二，試把複合結構中的另一部分暫時用括號圍起來，那麼該用的格就容易辨別了，如：
(6)This message is for (My father and) I or me.
(7)(Marry and) he or him went downtown together.
顯然的，(5)裏的代詞是賓格的"me", (6)裏的代詞是主格的"he".
⒉在比較結構裏，連接詞"as"或"than"後面，按理用主格式，但在口語中，人們常用賓格形式，學美式英語者，更是如此：
(8)a. You did as well as she.
b. You did as well as her.
(9)a. I am older than he.
b. I am older than him.
(a)和(b)兩種說法，都可接受。但如果"as"和"than"後頭分句的主語和詞動都要完整出現的話，這時的人稱代詞，就必須是主格，如下：
(10)You did as well as she did.
(11)I am older than he is .
此外，還有一點要注意，就是"as"和"than"後面雖然在語法上用主格好，用賓格也可，但是有時意思會有所不同。試比較(a)和(b)：
(12)a. Jason praised Maria more highly than I.
b. Jason praised Maria more highly than me.
(12)a和b都被接受，但(12)a等於(13)a，而(12)b等於(13)B：
(13)a. Jason praised Maria more highly than I did (= I praised Maria).
b. Jason praised Maria more highly than he praised me.
顯然，這兩句的深層意思大有差別。遇到這種情形，爲了避免誤解，不妨根據要表達的意思用完整的句式表達出來。換句話說，必要的話，要用(13)這句子。
不然，把(13)a變成(14), (13)b變成(15)也可：
(14)I did not praise Maria as highly as Jason did.
(15)Jason did not praise me as highly as he praised Maria.
