学生必须学习一门语言的语法规则。

Students must learn the ___grammatical rules of a language.

她的论文充满了结构良好、符合语法的句子。

Her essay was full of well-structured, ___grammatical sentences.

这篇文章很容易阅读，没有明显的语法错误。

The text was easy to read, with no obvious ___grammatical errors.