伴随状语到底是伴随主句谓语动词发生还是这两个动作同时发生?

不一定是同时发生，比如
Seeing the accident,I dailed 120
很显然，是看到了事故，然后才打120

你看一下嘛
分词作状语（关键找逻辑主语）
a)放在句首的分词往往看作时间状语1以及原因状语2
1. Looking (when I looked) at the picture, I couldn't help missing my middle school days.
2.Seriously injured, Allen was rushed to the hospital.
=As he was seriously injured, Allen was rushed to the hospital.
b)放在句中或句末常常看作为伴随状态(并列句)
The girl was left alone in the room，weeping（crying ）bitterly.
(但注意特殊：Generally/frankly speaking... / taken as a whole(总的来讲）不考虑逻辑主语，看作为独立成分)