He often helps me.
Who is at the door?It's me.
The bicyclebelongs to Tomandme.
出现并列主语或宾语时，其排列顺序为：单数时是第二、第三、第一人称(简称231)即you，he and I或you，her and me;复数时是第一、第二、第三人称(简称123)即we，you and they或us，you and them。
2.物主代词：形容词性物主代词作定语，后加名词;而名词性物主代词等于形容词性物主代词加名词。如：This is my book.=This book is mine.
Your pen is blue.Mine is blue,too.
She is a classmate of his.
The bike is hers.
Help yourself to some cakes.
I can look at myself in the mirror.
We do home work by ourselves.
I myself go to the airport to meet my uncle.
What's this(that)?It's a book.
What are these(those)?They are books.
(1)指物：It's a robot.
(2)指自然现象：It's raining now,but it will be fine soon.
(3)指时间：What time is it?It's 8 o'clock.
(4)指距离：It's twenty minutes' walk.
(5)作形式主语：It's important for us to fight pollution.
It took me half an hour to finish the work.
(6)作形式宾语：We think it necessary to relax from time to time.