you can help me?I-me-my-mineyou-you-your-yourshe-him-his-hisshe-her-her-herswe-us-our-oursthey-them-their-theirs什么时候才可以用这些人称代词呀,给一些例句

I am a student.
You and me can go together.
This is my book.
The bike is mine.(放在句末的一半用mine，句中的一般用my)
其他的可以以此类推 替换掉I、me、my、mine，基本都是这四种~

I am a boy(I做主语）
Can you help me?（me作宾语）
The girl is mine.——Is this red pen yours?——No,it"s not mine Mine is that blue one(可做表语,也可做主语)
God bless you.
Hope saviour on your journey.
Hey,guys,Is she your girl friend.
He is a criminal.
I like him.
His mum is a beauty.
She is a beauty.
I like her cooking.
It's not hers.
We are human beings.
They will like us.
Hey,beautiful ,this is our new bedroom.
Ours is over there.
They are my friends.
I like them.
The books are their favourite things.
The books are not theirs.