1. Auxiliary Verb: This is the most common use of "have." It helps form the perfect tenses (present perfect, past perfect, future perfect) and the passive voice.
* Examples:
* I have finished my homework. (present perfect)
* She had already left by the time I arrived. (past perfect)
* You will have completed the project by next week. (future perfect)
* The car was had been stolen. (passive voice)
2. Main Verb: "Have" can also be used as a main verb, meaning it expresses an action or state of being on its own.
* Examples:
* I have a new car. (possession)
* We have lunch at noon. (activity)
* They have a lot of fun. (state of being)
3. Modal Verb: "Have" can be used as a modal verb in the phrase "have to," meaning "must" or "need to."
* Example: I have to go to work.
It's important to understand the context of a sentence to determine the specific function of "have."