these stones,each___as much asfour tons,came from the Alps Mountains..

题目

these stones,each___as much asfour tons,came from the Alps Mountains..
A.weighted B.weighs C.to weigh D.weighing
选哪个?为什么?

答案

D.weighing
这是一道很容易选错的题目.
按汉语的习惯,each做主语,谓语动词理应用单数,即选 B.weighs .但按英语的语法,本句的each却不能做主语,因为前面已经有these stones 做主语；谓语也不是weighs,而是后面的came from.
each weighing as much as four tons,属于独立主格结构,做状语.这样理解才符合英语的语法.