That green pen is hers(改为同义句)
She  has a green pen.
Her pen is green.
It is  her pen that is green.
That book is hers. 意为“那本书是她的。”改为同义句时,我们可以这样表达:That is her book. (那是她的书。)
英语中,名词性物主代词可以作主语、宾语或表语。例如:I left my dictionary at home. Can I use yours?我把词典忘在家里了。我可以用你的吗
形容词性物主代词只能放在名词前作定语。例如:
This is my bike. 这是我的自行车。
That is her green pen .
那是她的绿色的钢笔。
her 她的,形容词性物主代词,后面加名词,hers她的,名词性物主代词,后面不能跟名词,单独使用