主格用在主语的位置，we

she

it

they

e.g:She

is

a

girl.

宾格一般用在句末，作句子的表语说明主语的性质。him

her

it

us

e.g:

It's

me.

形容词性物主代词后必须要加名词，Our

eraser.

名词性物主代词相当于形容词性物主代词加名词，This

is

our

eraser.=This

eraser

is

ours.

都是我们的意思