When they heard about the volcano they ran down to the village.

Hearing about the volcano, they ran down to the village.

Having finished his homework, he went to bed.

Having finished his homework, he went to bed.

Grammar Discovery

hear

run

at the same time

finish

go

before

V-ing 作状语时,与主语是主动关系,与谓语表示的动作或状态 同时或几乎同时发生的

如果V-ing 表示的动作发生在主句 子谓语之前，则要用V-ing 的完成式， 即：Having +P.P(过去分词)…, 主语+谓语