What part of speech is the word use?

The word "use" can be several parts of speech, depending on how it's used in a sentence:

* Verb: "I use a computer every day."

* Noun: "The use of computers has become widespread."

* Adjective: "This is a useful tool."

Let me know if you have a sentence in mind, and I can tell you which part of speech "use" is functioning as!