Factory chimneys discharge smoke into the atmosphere make it dirty.

工厂的烟囱往空气里排烟，造成大气污染。

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Factory chimneys discharge smoke into the atmosphere and make it dirty.

工厂的烟囱往空气里排烟，造成大气污染。

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It can discharge clean smoke.

排放洁净气体。

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It can discharge clean smoke.

排放洁净气体。

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