问as 和 while的一道GWD题目

GraceZhou

Q17:
The steel industry has changed radically over the last two decades, as large, integrated companies such as Bethlehem Steel once conducted operations from mining at one end of the process to shipping at the other have greatly downsized, or in some cases shut down altogether.

as large, integrated companies such as Bethlehem Steel
as large, integrated companies, such as Bethlehem Steel, that
with large, integrated companies, such as Bethlehem Steel, that
while large, integrated companies, such as Bethlehem Steel, that
and large, integrated companies such as Bethlehem Steel

正确选项为B，我错选了D
在PREP的语法笔记中有这样的知识点，大家说是这个题区分as和while的点吗？：
→as表示“当…的时候”时，其语义与when有细微差别。

When表示其连接的从句中谓语动作发生的那一具体的时间点，只是指那一会，或者说when描述的时间一般比较短；

而as引起时间状语从句，谓语一般为有延续性的动作，通常描述一段比较长的时间，最简单的例子。

如：as time goes by.

云南

这里只能用as, while只能表示转折，然而之意

watone

前后 句子 没有 转折的意思   不应该用 while

GraceZhou

但是while也有和as一样“当。。。的时候“的意思啊

云南

AS优先于while吧