"Do", "Be", or "Did"? Mastering English Auxiliary Verbs

Many English learners ask the same question:Why do I sometimes use "do", other times "be", and sometimes nothing at all?If you've ever said, "I don't listening" or "She did went home", you're not alone. These errors come from confusion about auxiliary verbs — especially in negative sentences and questions.

This article will help you understand how to use "do", "be", and "did" depending on the verb and the tense. You’ll learn when to use them, when not to use them, and how to avoid the most common mistakes — all explained clearly, with examples.

What is an auxiliary verb?

An auxiliary verb is a helping verb. It is used to make negative sentences, ask questions, or build verb tenses.In everyday English, the three most common are:

• do / does (present simple)

• am / is / are (present continuous)

• did (past simple)

But there’s one important exception: the verb "be" follows its own rules and does not need auxiliaries in the present or past simple.

Present Simple: Use "do" and "does" for most verbs

The present simple is used to talk about habits, routines, and facts.

Affirmative:

For example: I play the guitar.She eats vegetables. They like music.

Negative: For example: I don’t play tennis. He doesn’t drink coffee.

Questions: For example: Do you like chocolate? Does she live in London?

Important: Always use the base form of the verb.

For example: "She doesn’t play", not “doesn’t plays”. "Do you like it?", not “Do you likes it?”

3Present Simple with "be": No auxiliary needed

The verb "be" is different. You do not use "do" or does for questions and negatives.

Affirmative:

For example: I am tired. She is a student. We are ready.

Negative:

For example: I’m not tired. He isn’t here. They aren’t late.

Questions:

For example: Are you hungry? Is she your teacher?

Incorrect: Do you be hungry? or She doesn’t be late.

Correct: Are you hungry? / She isn’t late.

Present Continuous: Use "am / is / are" + verb-ing

This tense describes what is happening right now or around the current time.

Affirmative: For example: I am studying. She is reading a book. They are working from home.

Negative: For example: I’m not studying. He isn’t listening. We aren’t watching TV.

Questions:

For example: Are you working? What is she doing?

Important: Never use "do" with the present continuous. For example: Incorrect: I don’t listening Correct: I’m not listening

Past Simple: Use "did" for most verbs

Use this tense for actions that are finished and belong to the past.

Affirmative

For example: I watched a movie.

They visited Rome.

She called her friend.

Negative

Use did not (or didn’t) + base form.

For example:

I didn’t watch it.

He didn’t come.

We didn’t understand.

Questions

For example:

Did you see the film?

What did she say?

Important: Don’t combine "did" with the past form.

Incorrect: He didn’t went → Correct: He didn’t go

Incorrect: Did she saw it? → Correct: Did she see it?

6. Past Simple with "be": No auxiliary needed

Just like in the present, the verb "be" works on its own in the past.

Affirmative

For example:

I was tired.

He was at home.

They were late.

Negative

For example:

I wasn’t tired.

She wasn’t there.

We weren’t ready.

Questions

For example:

Was he sick?

Were they in class?

Incorrect: Did she be at school?

Correct: Was she at school?

Summary Table

Tense	Type of Verb	Auxiliary	Example (Affirmative)	Example (Negative)	Example (Question)
Present Simple	Most verbs	do / does	She works here.	She doesn’t work.	Does she work?
Present Simple	be	none	He is tired.	He isn’t tired.	Is he tired?
Present Continuous	All verbs	be + verb-ing	They are eating.	They aren’t eating.	Are they eating?
Past Simple	Most verbs	did	I went home.	I didn’t go.	Did you go?
Past Simple	be	none	She was happy.	She wasn’t happy.	Was she happy?

Learning to use "do", "be", and "did" correctly is a big step in improving your English. These small words are easy to forget, but they make a big difference in speaking and writing.

Keep practicing and don't worry about making mistakes — they are part of the process. Whether you’re learning through online education, taking private lessons in English, or following an English course with CPF in Vincennes, remember: every small improvement builds your confidence.

If you have questions, your favorite English teacher in Vincennes is here to help.

Practice: Correct the Mistakes

Here are some incorrect sentences. Try to correct them.

1. I don’t liking music.

2. She doesn’t goes to school.

3. He did saw the movie.

4. Are you play football?

5. We didn’t watched TV.

6. She doesn’t be late.

7. Did you be there?

Corrected versions:

1. I don’t like music.

2. She doesn’t go to school.

3. He saw the movie. OR He did see the movie.

4. Do you play football?

5. We didn’t watch TV.

6. She isn’t late.

7. Were you there?