1）现在分词可以作时间、原因、方式、伴随以及补充说明等状语,如：


Entering theroom,he saw many people were already there.（时间状语）
Knowing that itwas going to rain,he decided not to go out.（原因状语）
Laughing and talking,they went out for a walk together.（方式状语）
She stoodthere,waiting for the bus.（伴随状语）


2）现在分词还可以构成独立主格结构做状语,如：


I’ll come,weather permitting.天气好的话我就来.（条件状语）
Their room wason the second floor,its broad window overlooking the park.（补充说明）


3）一般情况下,句首的分词短语多作时间和原因状语,但是也可以根据说话人的强调程度放在句尾.