Native speakers can distinguish between grammatical and ungrammatical sentences even when they have never heard particular combinations before.

母语使用者可以分辨符合语法规则和不符合语法规则的句子，即使他们以前从没有听过这些特定的词语组合。

She talked ungrammatically but fluently.

她讲话不符合语法规则，却很流利。