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自考《英语(二)》真题练习:完成句子(11.29)

2017年11月29日    来源:自考365   字体:   打印

  单选题

  [完成句子]Heavy metals are persistent; they do not break down to other chemicals in the environment. Industrially polluted sites usually undergo intensive clean-up and rehabilitation because heavy metals are a health concern once they enter the food chain. Some trace metals are alleged to cause cancer and are also known to cause poisoning.

  Industrially contaminated sites usually require a thorough clean-up due to __________.

  A、the persistence of heavy metals

  B、industrially polluted soils

  C、naturally polluted soils

  D、rock and soil chemistry

  
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