1. She writes a letter.
- Noun: letter
- Verb: writes
2. She sings beautifully on stage.
- Adverb: beautifully (modifies the verb "sings")
3. He is incredibly talented at painting.
- Adverb: incredibly (modifies the adjective "talented")
4. They completed the project very quickly.
- Adverb: very (modifies the adverb "quickly")