Humans have been damaging the environment for centuries by overcutting trees and farming too intensively, and though some protective measures, like the establishment of national forests and wildlife sanctuaries, having been taken decades ago, great increases in population and in the intensity of industrialization are causing a worldwide ecological crisis.
(A) though some protective measures, like the establishment of national forests and wildlife sanctuaries, having been taken decades ago, great increases in population
(B) though some protective measures, such as the establishment of national forests and wildlife sanctuaries, were taken decades ago, great increases in population
(C) though some protective measures, such as establishing national forests and wildlife sanctuaries, having been taken decades ago, great population increases
(D) with some protective measures, like establishing national forests and wildlife sanctuaries that were taken decades ago, great increases in population (E) with some protective measures, such as the establishment of national forests and wildlife sanctuaries, having been taken decades ago, great population increases
I m confused between answer A and B I thought the tense in the parallel structure connected by 'And' should be the same. So it should be 'have been taken' not 'were taken'.
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发表于 2007-7-1 02:12:00
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