单选题 As the industry developing in these years, most of the rivers have been contaminated by sewage (污水).

【正确答案】 A

【答案解析】[解析] 本句意思：随着近年来工业的发展，很多河流都已被污水污染。contaminate污染，弄脏。pollute污染，玷污，破坏；downgrade使降职，低估；mix混合，混淆；blacken使变黑，抹黑，玷污。