英语
问题描述：
英语
Possibly the greatest advance in __ material came with the invention of a cheap way to make steel.
1.bridge-building 2.building of bridges
3.building a bridge 4.bridges are built
该选哪个呢?ing是动名词形式,所以123貌似都对啊
答
1,因为bridge-building 是形容material的起形容词作用,其他都不可以.