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1.                  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（B）

(E) with some protective measures, such as the establishment of national forests and wildlife sanctuaries, having been taken decades ago, great population increases

大家帮我看看，是不是题目错了，B 中的 were怎么想都觉得应该删除。

没人回？也许这题实在太简单了，但是看在本人是新人的份上，请哪位好心人士说明一下为什么答案是B。