War(warm?)air is frequently lighter as the molecules bump around, excited by the heat.

暖空气经常更轻一些，因为分子受到热量的激励而四处碰撞。

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Then, the sir column which was set around the stage will bump to the sky. The background in the stage will change.

随后，原先设置在舞台四周的气柱将同时冲向空中，舞台上的背景板发生了变换。

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Then, the sir column which was set around the stage will bump to the sky. The background in the stage will change.

随后，原先设置在舞台四周的气柱将同时冲向空中，舞台上的背景板发生了变换。

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