Though they still remain a major source of pollution, mainly sulphur dioxide and nitrogen oxides.

发电依旧是一个很大的污染源，主要的污染物是二氧化硫和一氧化氮。

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Though they still remain a major source of pollution, mainly sulphur dioxide and nitrogen oxides.

发电依旧是一个很大的污染源，主要的污染物是二氧化硫和一氧化氮。

youdao