Here's a breakdown:
Structure: "to" + base form of the verb
Examples:
* to run
* to eat
* to sleep
* to sing
* to learn
Functions:
* Noun: The infinitive can act as the subject of the sentence.
* To sleep is important for good health.
* Noun: The infinitive can act as the object of the verb.
* I love to sing.
* Adjective: The infinitive can describe a noun.
* I have a lot of work to do.
* Adverb: The infinitive can modify a verb, adjective, or another adverb.
* He was eager to learn.
* It's too cold to go outside.
Note: Sometimes the "to" is omitted from the infinitive. This is called the bare infinitive.
* *Let me * help * you.*
* *I made him * go * to the store.*
These are usually used after specific verbs like "let" or "make."
Understanding infinitives can help you construct more complex and varied sentences.