1. Subject is singular and the verb is in the present tense:
* Singular subject + has + past participle
* *The dog has eaten** all the food.
* *She has finished** her homework.
* *The book has been** borrowed by someone.
2. Subject is a plural noun, but refers to a single unit:
* Plural noun (single unit) + has + past participle
* *The team has won** the championship. (Team is considered a single unit)
* *The government has passed** a new law. (Government acts as one entity)
3. With singular indefinite pronouns:
* Indefinite pronoun (singular) + has + past participle
* *Someone has stolen** my wallet.
* *Everyone has finished** their meal.
* *Nothing has changed**.
4. When forming the present perfect tense:
* Subject + has/have + past participle
* *I have seen** that movie before.
* *They have been** to Paris.
* You have read this book, haven't you?
Here's a quick way to check if you should use "has":
* Ask yourself: "Does the subject do the action?" If yes, and it's in the present tense, use "has" (if the subject is singular).
Let me know if you have any other grammar questions!