Understanding the Auxiliary Verb "To Do"

The auxiliary verb "to do" plays a vital role in English grammar, mainly used for forming questions, negatives, and emphatic statements. Mastering its correct usage improves sentence structure and communication skills.

➤ What Is the Auxiliary Verb "To Do"?

The verb "to do" functions as an auxiliary (helping) verb when it assists the main verb in forming questions, negatives, and emphatic sentences. It changes according to tense and subject.

• Present tense: do, does

• Past tense: did

• Base form: do

When used as an auxiliary verb, "to do" is always followed by the base form of the main verb.

➤ Usage of "To Do" with Examples

✔ Forming Questions

"To do" helps create yes/no questions and wh-questions.

• Yes/No Question:

  • Do you like coffee?

  • Does she work here?

  • Did they arrive on time?

• Wh-Question:

  • Where does he live?

  • Why did they leave early?

  • What do you mean?

✔ Forming Negative Sentences

"To do" is used to form negatives by adding "not".

• Present Simple Negative:

  • I do not (don’t) like fish.

  • She does not (doesn’t) know him.

• Past Simple Negative:

  • They did not (didn’t) see the message.

✔ Adding Emphasis

"To do" is used to add emphasis to a statement.

• I do like your idea!

• She does appreciate your help.

• He did call you yesterday.

➤ Common Mistakes with "To Do" (With Corrections and Explanations)

❌ Mistake 1: Using "Do" with Modal Verbs

Incorrect: He does can swim.
Correct: He can swim.
Explanation: "To do" is not used with modal verbs (can, must, should, etc.).

❌ Mistake 2: Using "Does" with a Plural Subject

Incorrect: They does play football.
Correct: They do play football.
Explanation: "Does" is only used with he, she, it (third-person singular).

❌ Mistake 3: Using "Do" Instead of "Did" in the Past

Incorrect: Yesterday, I do my homework.
Correct: Yesterday, I did my homework.
Explanation: The past simple form of "do" is "did" for all subjects.

❌ Mistake 4: Using the Base Verb After "Did" in a Positive Sentence

Incorrect: She did went to the store.
Correct: She did go to the store.
Explanation: After "did," always use the base form of the verb, not the past tense.

➤ 4 Exercises on the Auxiliary Verb "To Do"

✔ Exercise 1: Fill in the blanks with "do," "does," or "did"

1. ____ you like ice cream?

2. She ____ not understand the question.

3. ____ they visit you last summer?

4. He ____ his homework before dinner.

✔ Exercise 2: Choose the correct form of "to do"

1. He (do/does) not like spicy food.

2. What (do/did) you say?

3. They (does/did) go to school yesterday.

4. She (do/does) her work on time.

✔ Exercise 3: Correct the mistakes in these sentences

1. He do not speak Spanish. → Correct it: __________

2. Where did she went? → Correct it: __________

3. They does like pizza. → Correct it: __________

4. I did not ate lunch. → Correct it: __________

✔ Exercise 4: Write sentences using "to do" in different forms

• A question using "does"

• A negative sentence using "did not"

• An emphatic sentence using "do"

• A past simple question using "did"