What part of speech does be + adjective equal to? Adverb? Preposition?

You are beautiful, are is a copula, beautiful is a predicative, the sentence structure is: main system table

RELATED INFORMATIONS

1. What's the difference between English adjectives and adverbs in predicative, complement, attributive and adverbial
2. As + the original level of adjective or adverb + as. What is the original level of adverb,
3. The differences and usages of English adjectives and adverbs More specific.
4. The different usages of adverbs and adjectives in English. What are the differences?
5. as…… In the middle of as is the usage of noun, adjective and adverb,
6. He is one of popular teachers?
7. What does one of the + adjectives mean?
8. Must the be added to the superlative of the adjective after one of? For example: teahouse is one of Lao She's most famous plays. In this sentence, the superlative of famous is not added with the. When is the superlative of adjective after one of not added with the?
9. It's + one of + adjective superlative In this sentence pattern, do you add the most advanced adjective?
10. What is a word that ends with a consonant and a Y? I can't understand this sentence. For example, where is the consonant of city? Where is the consonant? I can see the ending with y. teach me Is the consonant here the first letter, or where?
11. How to use nouns, verbs, prepositions, adjectives and adverbs? What words modify what words?
12. The usage of "much" and "more" How to modify comparative grade and how to distinguish it?
13. I don't know how to use "much" and "much more" to modify adjectives? For example, I know it's much cheaper, but I want to know, why can't I use much more soap?
14. Usage of "much more" It's a combination
15. Many and much are adjectives, but their comparative more is an adverb. Why?
16. The difference and usage of more, much and much more in English
17. What do English adjectives, nouns, adverbs, prepositions and verbs modify, how to use them and what are their collocations?
18. What other words in English besides noun verb adjective adverb preposition?
19. What's after English nouns, verbs, adjectives, prepositions and adverbs?
20. What are nouns, pronouns, verbs, auxiliary verbs, transitivity / intransitivity, adjectives, adverbs, prepositions and usage in English Also, what should be added and what should not be added? The more detailed the better, the more the better I've learned and forgotten