1、主格（Subject Case）
Mike(名词) hit the ball. He(代词) ran to first.
Sally hit the ball. She ran to second.
Mike and Sally ate lunch. They felt full.
The dog rummaged through the trash. It was looking for a bone.
2、宾格（Object Case）
Mike called Sally. He asked her the time.
I walked down the street. John saw me. He said hello to me. I said hello to him.
3、单数和复数
单数 Subject | I you he/she/It
Object | me you him/her/It
复数 Subject | we you they
Object | us you them
4、所有格（Possessive）。表示拥有什么。
My car is outside. The car is mine.
Your car is outside. The car is yours.
His/her car is outside. The car is his/hers.
Our car is outside. The car is ours.
Their car is outside. The car is theirs.
