Of all the vast tides of migration that have swept through history, maybe none is more concentrated as the wave that brought 12 million immigrants onto American shores in little more than three decades.
"4. Of all the vast tides of migration that have swept through history, (maybe none is more concentrated as) the wave that brought 12 million immigrants onto American shores in little more than three decades.
(A) maybe none is more concentrated as (B) it may be that none is more concentrated as (C) perhaps it is none that is more concentrated than (D) maybe it is none that was more concentrated than (E) perhaps none was more concentrated than " 始终没明白为什么不能用is而必须用was呢
A/B不作为备选答案因为as/than, more than是固定搭配,more as的搭配直接被排除。 但是如果偏要纠结一下is/was, 那么从前半句 of ...tides ...migrations that have ...,说明这些移民潮都是已经发生的,既然是已经发生的,拿出来和另一个已经发生的做比较肯定是was
不知道讲明白没有
另外have 怎么可能是修饰migration呢? migration是单数 have ...是完成时态的verb, 从没见过verb 做modifier的说法。