be, do and have

These three do two jobs. They can be the main verb of a sentence, and they can help another verb build a tense, a question or a negative. Almost every structure in Part B uses one of them.

Their forms

The verb be
Subject	Present	Past	Negative
I	am	was	am not / was not
You / We / They	are	were	are not / were not
He / She / It	is	was	is not / was not

The verb do
Subject	Present	Past	Negative
I / You / We / They	do	did	do not (don't) / did not (didn't)
He / She / It	does	did	does not (doesn't) / did not (didn't)

The verb have
Subject	Present	Past	Negative
I / You / We / They	have	had	have not (haven't) / had not (hadn't)
He / She / It	has	had	has not (hasn't) / had not (hadn't)

What each one is for

be

1. To say what or how something is: She is a doctor. I am tired.
2. To build continuous tenses: She is reading.
3. To build the passive: The letter was written by Ali.

do

1. To make negatives and questions in the present and past simple: Do you know? He does not know.
2. As a main verb meaning to perform: I do my homework at night.
3. For emphasis: I do understand.

have

1. To own or possess: I have two brothers.
2. To build perfect tenses: She has finished.
3. In have to = must: I have to leave now.

Helping verb mistakes and their corrections
Wrong	Right	Why
I am agree with you.	I agree with you.	Agree is already a verb; it needs no am.
She have two sisters.	She has two sisters.	He, she, it take has.
He don't like tea.	He doesn't like tea.	He, she, it take doesn't.
I have 25 years.	I am 25 years old.	Age uses be, not have.
There is many students.	There are many students.	There is for one, there are for more than one.

Check yourself

Fill in the right form of be, do or have.

I ___ a student and my brother ___ an engineer.
Show the answer
am … is
She ___ finished her homework already.
Show the answer
has
They ___ not come to class yesterday.
Show the answer
did
___ he speak English?
Show the answer
Does
Fix: I am agree with your opinion.
Show the answer
I agree with your opinion.
Fix: She have three brothers.
Show the answer
She has three brothers.
Fix: I have 22 years.
Show the answer
I am 22 years old.
Fix: There is many students in the hall.
Show the answer
There are many students in the hall.

More practice on this topic: 13 exercises →