BE (verb) American English definition and synonyms | Macmillan Dictionary

Be

can have many different forms depending on its subject and on its tense.

Be

can be used in the following ways:

as an

auxiliary verb

in progressive verb tenses or in passive forms (followed by a present participle or a past participle):

The train is leaving.

A window was broken.

as a

verb

(followed by an infinitive with “to”):

All books are to be returned by Friday.

The party was to be a surprise.

as a

linking verb

(followed by an adjective or noun complement):

Dad was sick.

His wife is a doctor.

(followed by an adverb or preposition):

The children are in bed.

Questions and negatives that are formed without “do”:

Are you busy?

The book was not expensive.

Be

is often used in tag questions:

You weren’t listening, were you?

It’s cold, isn’t it?