Be nice to your sister! (imperative)
I like to be at my house. (infinitive)
Present
This form of the verb is mainly used in the simple present, and its meaning can change depending on the use in the context. Also, when writing, the present form of the to be verb can be shortened.
The verb be is used as an auxiliary verb and it can also be used as a main verb. The verb be is irregular. It has eight different forms: be, am, is, are, was, were, being, been. The present simple and past simple tenses make more changes than those of other verbs.
I am late.
We are late.
You are late.
You are late.
He is late.
They are late.
I was late.
We were late.
You were late.
You were late.
She was late.
They were late.
The present participle is being.
He is being very helpful these days. The past participle is been.
We have been ready for an hour.
The present simple tense forms of be are often contracted in normal speech. Note that the contracted form of they are is spelled they’re, and not their which is the possessive form of they.
I’m here.
We’re here.
You’re here.
You’re here.
He’s here.
They’re here.
Any form of be is made negative by adding not immediately after it. In speech, some forms of be also have contracted negative forms. Some of these forms emphasize the negative.