Battery electric bicycle on the problem of pollution.

电池的污染问题的电动自行车。

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Everybody knows that there is serious problem of water pollution on the earth.

大家都知道，在地球上水体污染是严重的问题。

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Everybody knows that there is serious problem of water pollution on the earth.

大家都知道，在地球上水体污染是严重的问题。

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