Most environmental problems exist because adequate measures for preventing them

游客2024-11-01  8

问题 Most environmental problems exist because adequate measures for preventing them _________ taken in the past.

选项 A、was not
B、were not
C、were not being
D、being not

答案 B

解析 被动语态的时态、数、性的一致,主要由助动词来表示,要注意它们与主语的一致。此处从句的主语measures是复数,因此选择答案B。
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