He said it was a historic event and that he is certain it will inaugurate a new era and a new relationship between the two countries.

VOA: standard.2009.04.17

It's only endemic, that means only naturally occurring in certain countries.

这是种地方性疾病,这意味着仅在几个特定国家中发病

耶鲁公开课 - 生物医学工程探索课程节选

why some countries have chosen or established certain forms of government,

为什么有些国家选择或建立某些形式的政府，

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