独立主格结构的作用
1．作状语
1）表示时间
His homework done（=After his homework was done），Mary decided to go shopping.
2）表示原因
There being no buses（=Because there were no buses），we had to walk home.
3）表示条件
Weather permitting（=If weather permits），we’ll go to play basketball.
4）表示方式或伴随
He sat at the table, head down.
2．作同位语
Many people joined in the work, some of them women and children.
3．作定语
Close to the bank, we saw deep pools, the water blue like the sky.
（三）有时用with/without引导的复合结构作状语，在句中可作定语或状语。如：
Do you know the girl with a basket on her back ? | 
