Explain the concept of agreement in syntax.

**Agreement** in syntax refers to the grammatical rule that requires certain parts of a sentence to match or correspond with each other in terms of features such as number, gender, person, or case. This ensures consistency and coherence within a sentence. Key aspects of agreement include:

1. **Subject-Verb Agreement**: The verb must agree with the subject in number (singular or plural) and sometimes person. For example, in English:

   - Singular: "She **writes** every day."

   - Plural: "They **write** every day."

2. **Noun-Adjective Agreement**: In languages with gender and case marking, adjectives and nouns must agree in gender, number, and case. For example, in French:

   - Masculine singular: "un **grand** homme" (a tall man).

   - Feminine singular: "une **grande** femme" (a tall woman).

3. **Pronoun-Antecedent Agreement**: Pronouns must agree with their antecedents (the nouns they refer to) in number, gender, and person. For example:

   - Singular: "John lost **his** keys."

   - Plural: "The students lost **their** books."

Agreement helps maintain grammatical harmony and clarity in sentences, ensuring that all elements of a sentence align correctly with each other.