1.He cut off the electricty quickly so that an accident was prevented.
He cut off the electricty quickly, preventing an accident.
--ing分词作结果状语
2.The old man was fast asleep and held a book in his hand.
The old man was fast asleep, helding a book in his hand.
--ing分词作伴随状语
3.As he was crossing the road, he was run over by a car.
As crossing the road, he was run over by a car.
--ing分词作原因状语
4.As he didn't know English, he couldn't understand the film.
Not knowing English, he couldn't understand the film.
--ing分词作原因状语
应该不会错哦~