In English, what are the differences and connections between predicates and subject complements?

Subject complements are usually placed before the subject or after the predicate verb, and of course after the past participle of the passive voice of the predicate verb.

General predicates are subject complements.

For example, i feel nervous.

nervous is both a predicate and a subject complement.

In passive voice, the subject complement is not a predicate.

Such as He was caught alive.

alive is a subject complement, not a predicative

①The subject complement is before the subject and followed by a comma

Example: Tired and sleepy, I went to bed

② Sometimes it is located after the subject, with commas before and after

Example: Chen, only 1.30 meters tall, won the first prize.

③After the predicate verb

Example: He died young

He was found died.

④In addition to adjectives, nouns, numerals, and infinitives, Participles, prepositional phrases, and clauses can also be used as subject complements. Example: He came home quite changed.