Somebody says, "What is a mare?" "Well, it's a female horse." "Well, it's a female horse" is the metalingual function.

有人问“什么是母马“，“母马就是雌性的马“,“母马就是雌性的马“这句话就是元语功能。

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In the grammatical sense, this word is the means or principal of predication whereby we say one thing is another thing: the mare is the female of the horse, for example.

从语法的角度来看，is这个词是,我们声明一个东西是另一个东西的方式或者？委托：,例如说，母马是马中的雌性。

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