是分词的一种有逻辑主语的一种形式.在句子中做状语,如
Tim permitting ,we will visit that city.= if time permits ,we will visit that city.
I being ill , all my classmates came to see me yesterday.=Because I was ill ,all my classmates came to see me.
There being no bus, we had to walk home .= Because there was no bus, we had to walk home.
Tom walking in the street , a car stopped before him.=when Tom was walking in the street, a car stopped before him.
独立主格中的逻辑主语不是后面句子中的主语,所以要用其主格形式写出来,放在非谓语动词（doing ,done ,to do）的后面.可以改写成一个状语从句.如上面的例子.