When to use be verbs and modal verbs in English?

First of all, verbs can be divided into notional verbs, auxiliary verbs, auxiliary verbs and modal verbs.

The notional verbs, divided into transitive verbs and intransitive verbs, are all verbs with practical significance and can be used as predicates independently. The difference is that transitive verbs can follow the object directly (for example, English can follow students), while intransitive verbs cannot follow the object directly, but they should form prepositional phrases together with prepositions (for example, listen must be followed by the preposition "to" to follow the object). Truly meaningful verbs account for the vast majority of English verbs.

A copula is used as a predicate verb followed by a predicate in a sentence. Common copula verbs are be, seem, look, become, get, grow, feel, apparent, remain, turn and so on.

Auxiliary verbs can only form tense, voice, mood and other verb forms with active words. Such as do, shall, will, have, as, etc.

Modal verbs express the speaker's mood or modality, such as ability, obligation, necessity, guess, etc. Common modal verbs are can/may/must/need/over/dare, etc. Modal verbs cannot be predicated alone, but must be predicated with other entity verbs. For example, the modal verb "must" in the sentence "You must go to school now" must be predicated with the entity verb "go".

It can be seen that the be verb is actually a verb, often followed by a slogan, and the predicate is mostly an adjective (phrase) or a noun (phrase). She is a beautiful girl. Or she's beautiful.