问题详情：
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Mankind must have in mind that it will be years, even centuries, ________the environment recovers from the damage they make to it.
A. that B. before C. when D. since
【回答】
【解析】选B。考查状语从句的连接词。句意:人类必须要意识到遭到他们破坏的环境要恢复过来至少需要很多年甚至几个世纪。It will be. . . before. . . “要过多少时间才能够……” 。
知识点：连词
题型：选择题
