Are nouns verbs and modifiers the three main English word classes?

That's a good starting point, but it's not quite complete! While nouns, verbs, and modifiers are crucial parts of English grammar, there are a few more important word classes to consider:

The Big Four:

1. Nouns: Words that name people, places, things, or ideas (e.g., cat, London, happiness).

2. Verbs: Words that describe actions or states of being (e.g., run, think, exist).

3. Adjectives: Words that modify nouns, describing their qualities (e.g., big, red, happy).

4. Adverbs: Words that modify verbs, adjectives, or other adverbs, describing how, when, where, or to what extent something happens (e.g., quickly, yesterday, very).

Beyond the Basics:

While these four classes are fundamental, there are other important word classes:

* Pronouns: Words that replace nouns (e.g., he, she, it, they).

* Prepositions: Words that show relationships between nouns and other words (e.g., on, under, beside).

* Conjunctions: Words that join words, phrases, or clauses (e.g., and, but, because).

* Determiners: Words that come before nouns to specify them (e.g., the, a, this, those).

* Interjections: Words that express strong emotions (e.g., Wow!, Ouch!, Hey!).

So, while nouns, verbs, and modifiers are essential, the full picture of English word classes is a bit richer!