事实确凿
The facts are conclusive.
以上为机器翻译结果，长、整句建议使用 人工翻译 。
记住，唯一需要担心的是笑颇具传染性，另一科学事实确凿地证明了这一点。
The only concern to keep in mind is that smiling is very contagious and it is, definitely, another proved scientific fact.
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