Question

【题目】In the past, many rivers were ______________(污染) seriously, but now they are cleaned up.

Answer 1

【答案】polluted

【解析】

句意：在过去，许多河流被严重污染，但是现在它们被清理干净了。

“污染”可用pollute表示，动词；分析句子可知，本句主语many rivers是动作pollute的承受者，此处应使用被动语态结构，所以用其过去分词形式。故填polluted。