慢性阻塞性肺病的最普遍症状是呼吸困难(或“透不过气来”)，痰(气管中唾液和粘液的混合体)出现异常，以及慢性的咳嗽。

The most common symptoms of COPD are breathlessness (or a "need for air"), abnormal sputum (a mix of saliva and mucus in the airway), and a chronic cough.

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由于唾液是传染的重要媒介，而且结核杆菌能在痰中存活一整天，因此在很多国家，随地吐痰就成为违法行为了。

As saliva is one of the main vectors of infection and the tuberculosis bacillus can survive in spit for a whole day, spitting was outlawed in numerous countries.

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痰来自肺部，并且通常很粘稠；而唾液来自口腔，是稀薄和水状的。

Sputum comes from your lungs and is usually thick, while saliva comes from your mouth and is thin and watery.

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