Ashewassettingoutthatafternoon,therewasonlyonethingtodo.这是as引导的什么从句

Question

As he was setting out that afternoon,there was only one thing to do. 这是as引导的什么从句

Answer 1

那天下午当他出发的时候,只有一件事情要做.
很明显,as引导时间状语从句,“当……时候”,而was setting out意思是“正要出发”,跟 be leaving for 表示的状态是一样的.
当主句、从句动作同时进行,从句动作的时间概念淡化,而主要表示主句动作发生的背景或条件时,只能用 as.这时,as常表示“随着……”；“一边……,一边……”之意.
① As the time went on,the weather got worse．（as表示“随着……”之意）
② The atmosphere gets thinner and thinner as the height increases．随着高度的增加,大气越来越稀薄.