Here's why:
* Definite articles (like "a," "an," and "the") are words that introduce or specify a noun. They signal whether the noun is specific or general.
* Common nouns are words that refer to general types of people, places, or things (e.g., "dog," "city," "chair").
* Pronouns are words that replace nouns (e.g., "he," "she," "it," "they").
Example:
* "A" proper abstract (This refers to a specific abstract, which is likely a noun)
Let me know if you have any other questions about grammar!