Language code hierarchies do not guarantee that all languages with a common prefix will be understood by those fluent in one or more of those languages.

语言代码层级并不保证拥有相同前缀的语言能够被它所描述的一个和多个语言流畅的理解。

youdao

I don't know how strong I'll be if I move to a foreign country and try to speak in another language with fluent speakers.

我不知道如果我到另一个国家，和另一种语言努力地跟那些说话流利的人交流，那时我会有多坚强。

youdao

A diplomat should be fluent in foreign language.

外交官的外语，应该要流利。

youdao

To be functionally fluent in a language, for instance, in most cases you need about 1, 200 words.

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