新三17课中的两个语法问题They support the cables from which the bridge has been suspended

题目

新三17课中的两个语法问题They support the cables from which the bridge has been suspended
1,It has been estimated that if the bridge were packed with cars,it would still only be carrying a third of its total capacity.这里面的carrying 为什么要用现在分词呢,从句是一般过去时,主句应该用would加动原就行了,为什么用现在进行时
2,They support the cables from which the bridge has been suspended,为什么这个定语从句用完成时,这段的语态都是过去时时啊,为什么support用一般现在时,是对客观事实的陈述吗?那从句为什么用完成时呢

答案

根据来提顺序,答复如下：
1） 先肯定这里的 that 引出的是实际主语.注意,It has been estimated that 据估算 .,其后 if the bridge were packed with cars, it would still only be carrying a third of its total capacity 是一句虚拟语气,然而,这一虚拟与事实比较接近.这里的 be carrying 用得比较特殊,是有这样的用法.
2） They support the cables from which the bridge has been suspended. 这里不能孤立地看这一句句子,应当与前文同时看 “Above the surface of the water, the tower rise to a height of nearly 700 feet.” 与此事实相同,当然也要用一般现在时态,但大桥已经作为一座完工项目,作为时态呼应,此定语从句就应当用完成时态.