Both practice and experimental studies of other scholar prove that proper natural experiment can make people feel more cheerful and healthy than typical air conditioning experiment.

生活实践以及其他学者的研究都证明，适宜的自然环境较常规空调环境更能给人带来愉悦与健康。

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The cheerful morning air is being shared by a pair of hares.

一对野兔双双享受着清晨令人愉快的空气。

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Nearby, a fox heard the cheerful call and carefully sniffed the air.

在近处，有一只狐狸也听到了这快乐的召唤，她小心翼翼地嗅了嗅空气。

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Owners inevitably paint the exteriors in a cheerful riot of bright red, green, orange, blue and yellow and line the un-air-conditioned cabs with teakwood to keep them cooler in India's searing heat.

FORBES: The Next People's Car