1. The students learn English.
The students, English (Noun)
Learn (Verb)
The students = They (Pronoun)
2. They walk quickly.
They (Pronoun)
Walk (Verb)
Quickly (Adverb)
3. Robert lives and teaches in California
Robert, California (Noun)
Lives, Teaches (Verb)
and (Conjuction)
in (Preposition)
4. Wow! This tastes good.
Wow! (Interjection)
This (Pronoun)
Tastes (Verb)
Good (Adjective)