英语中的人称代词（Personal Pronouns）有主格、宾格和所有格之 分,如：
I,me,my ; he,him,his ; they,them,their等.
顾名思义,主格（The nominative case）用作主语,宾格（The objective case）用作宾语,所有格（The possessive case）则表示所有之物.
在实际运用中,主格和宾格代词有时会混淆.下面是常见的问题：
⒈在复合结构里,人称代词的主格和宾格在单独使用时,没有问题,如很少人会犯下这样的错误：
*（1）Wilcox spoke to I.
*（2）Her knew what had happened.
但在复合结构中,错误就难免了,如：
*（3）Wilcox spoke to my friend and I.
*（4）He and her knew what had happened.
*（5）This is between you and he.
这种错误是可避免的.第一,在有介词的复合结构中,特别要注意,第二个人称代词,必须用宾语,如："for you and me"和 "between Maria and him".第二,试把复合结构中的另一部分暂时用括号围起来,那么该用的格就容易辨别了,如：
（6）This message is for （My father and） I or me.
（7）（Marry and） he or him went downtown together.
显然的,（5）里的代词是宾格的"me",（6）里的代词是主格的"he".
⒉在比较结构里,连接词"as"或"than"后面,按理用主格式,但在口语中,人们常用宾格形式,学美式英语者,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）两种说法,都可接受.但如果"as"和"than"后头分句的主语和词动都要完整出现的话,这时的人称代词,就必须是主格,如下：
（10）You did as well as she did.
（11）I am older than he is .
此外,还有一点要注意,就是"as"和"than"后面虽然在语法上用主格好,用宾格也可,但是有时意思会有所不同.试比较（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等于（13）a,而（12）b等于（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.
显然,这两句的深层意思大有差别.遇到这种情形,为了避免误解,不妨根据要表达的意思用完整的句式表达出来.换句话说,必要的话,要用（13）这句子.
不然,把（13）a变成（14）,（13）b变成（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.