[ADJ 形容词]语法的;文法的Grammatical is used to indicate that something relates to grammar.
[ADJ n]
Should the teacher present grammatical rules to students?
老师是否应该给学生讲授语法规则?
...grammatical errors.
语法错误
grammatically
...grammatically correct language.
合乎文法的语言
2
[ADJ 形容词]符合语法规则的;符合文法的 If someone's language is grammatical, it is considered correct because it obeys the rules of grammar.
...a new test to determine whether students can write grammatical English.
考查学生是否能用符合语法规则的英语进行写作的新型考试
grammatically
One in five undergraduates cannot write grammatically.
有1/5的本科生写作不合语法规则。
Oxford
gram·mat·ical/ɡrəˈmætɪkl; NAmEɡrəˈmætɪkl/adjective1connected with the rules of grammar 语法的;文法的◆a grammatical error语法错误2correctly following the rules of grammar 符合语法规则的;合乎文法的◆That sentence is not grammatical.那个句子不合语法。▶gram·mat·ical·ly/ɡrəˈmætɪkli; NAmEɡrəˈmætɪkli/adverb◆a grammatically correct sentence语法上正确的句子gram·mat·ical/ɡrəˈmætɪkl; NAmEɡrəˈmætɪkl/gram·mat·ical·ly/ɡrəˈmætɪkli; NAmEɡrəˈmætɪkli/