they是人称代词主格形式，其形容词性物主代词是their，名词性物主代词是theirs。
例句：Their dishes were made of wood.他们的盘子是用木头制成的。
they是代词，作主语。their是they的形容词性物主代词，后面加名词。
their是所有格（物主代词），意思是他们的
they通常作为主语，意思是他们
them是宾语，跟在动词后面，意思是他们
them(他她它们)是they的宾格，一般在介词后。their(他它她们的)是they的形容词性物主代词，后面加名词。they(他它她)，是代词，作主语.
their他们的是形容词性物主代词。them，他们通常作"宾格"用
例句:
I borrowed this book from them.
They lent this book to me.
Their book is very intersting.
