Her ________ of English grammar is amazing.

The word 'command' fills the blank in the sentence 'Her________ of English grammar is amazing.' This indicates an excellent knowledge and ability in English grammar based on syntax principles like subject-verb agreement and proper pronoun usage.

Explanation:

This implies that the person has a strong knowledge and ability to use English grammar effectively. The principles of English syntax, which involve rules like subject-verb agreement and the use of pronouns, help determine whether a sentence is grammatically correct or not. For example, the sentence "Herself have wrote these excellent book" is incorrect because it violates several rules of English grammar. The pronoun "herself" is reflexive and cannot act as the subject of a verb, the verb "have wrote" should be "has written" to maintain proper tense and subject-verb agreement, and "excellent book" should be pluralized to "excellent books" to match with the past participle "written". Correct pronoun usage, proper verb forms, and accurate singular or plural nouns are essential for crafting grammatically correct sentences in English.