GWD28-Q20 SC新问题。。。求助

笨蛋加油

In the 1820’s, anthracite coalfields opened in eastern Pennsylvania, and when canals and eventually railroads reached into the region, there were substantial supplies of coal that was exported to the nation’s growing mills, forges, factories, and railways.

A.    when canals and eventually railroads reached into the region, there were substantial supplies of coal that was
B.    once canals and eventually railroads reaching into the region, there were substantial supplies of coal having been
C.    with canals and eventually railroads reaching into the region, there had been substantial supplies of coal
D.    canals and eventually railroads reached into the region, with substantial supplies of coal being
E.    as canals and eventually railroads reached into the region, substantial supplies of coal were
答案是E哈，我做的时候看到A觉得there be 不好，就继续往下看，看到E了，本来觉得挺好，可是突然发现supplies怎么能被 exported 呢？不合逻辑啊，于是就选了A。。。可是一看答案是E，我就纠结了。。。请高人指教！谢过~

笨蛋加油

幸运E枪兵

supply除了“提供”之外应该还有“补给品”的意思吧……

笨蛋加油

supply除了“提供”之外应该还有“补给品”的意思吧……

-- by 会员 幸运E枪兵 (2012/2/27 0:34:43)

哦~对哈，恍然大悟，谢啦