En que se parecen las oraciones copulativas y predictivas?

A copula is a verb that joins the subject of a sentence or clauseto a subject complement. For example, the word is functions as a copula in the sentences "Jane is my friend" and "Jane is friendly." Adjective: copular. Also known as a copular verb or a linking verb. Contrast with a lexical verb and a dynamic verb.

The primary verb be is sometimes referred to as "the copula." However, while forms of being (am, are, is, was, were) are the most commonly used copulas in English, certain other verbs (identified below) have copular functions as well.