1. 作状语
1) 表示时间 如:
Her homework done (=After her homework was done),Lucy decided to go shopping.
2) 表示原因 如:
There being no buses (Because there were no buses),we had to walk home.
3) 表示条件 如:
Weather permitting (If weather permits), we will go to play football.
4) 表示方式或伴随 如:
He rushed into the room, his face covered with sweat.
2. 作同位语 如:
There are two doors, one leading to the bedroom, the other (leading) to the kitchen.