It’s snowing outside and I have cold.
It’s snowing outside and I am cold.
She has 10 years.
She is 10 years old.
What day do we have today?
What day is it today?
You have right.
You are right.
Is there a computer at you?
Do you have a computer?
She is three years old.
You are right and I am wrong.
I am cold - what’s the temperature in here?
I have a cold, in fact, I think I am getting a temperature.
to be is used rather than to have in the following situations: to be + right, wrong, cold, hot, thirsty, hungry.
to be is used in relation to ages: He is 45 years old.
to have is also used as an auxiliary verb to form the present perfect and past perfect of every verb, whether it is transitive or intransitive. to be is only used as an auxiliary to form the passive.