To Be: Affirmative

To Be is an irregular verb and, in the affirmative form, it has this structure:
Subject + to be + …

We use to be as a linking verb between other classes of words, it gives us more details about the condition of the subject.

To be is used with:

1. Nouns;
2. Adjectives;
3. Prepositional phrases (or complements).

Short form

The short form is used in spoken language or in informal writing.