Using 'Didn't', 'Doesn't', and 'Did Not' Correctly

Do you know when to use didn't, doesn't, and did not? These auxiliary verbs are essential for forming negative sentences in English. Test your knowledge with these interactive exercises!

Look at these examples to see how these auxiliary verbs are used:

She doesn't like coffee. (Present simple negative - third person singular)
They didn't come to the party yesterday. (Past simple negative - contracted form)
I did not finish my homework. (Past simple negative - full form, more formal)

Grammar Test 1

Try this exercise to test your grammar. Choose the correct auxiliary verb for each blank.

1. She understand the lesson yesterday.

2. My brother eat meat. He's vegetarian.

3. We have time to finish the project last week.

4. The students complete their assignments on time. (formal statement)

5. He work on weekends.

6. I see you at the meeting yesterday.

7. The cat like being touched by strangers.

8. They attend the conference last month.

9. She speak English very well yet.

10. The witness provide accurate information during the trial. (formal context)

Grammar Explanation

Understanding when to use didn't, doesn't, and did not depends on tense, formality, and subject-verb agreement.

When to use DOESN'T

We use doesn't (does not) for:

Present simple negative with third person singular: he, she, it
- She doesn't like chocolate.
Habits and general truths in present:
- The sun doesn't rise in the west.
Informal and conversational contexts:
- He doesn't want to come with us.

When to use DIDN'T

We use didn't (did not) for:

Past simple negative (all persons):
- I didn't go to school yesterday.
Informal and conversational contexts:
- They didn't call me back.
Most common in everyday speech:
- We didn't see the movie last night.

When to use DID NOT

We use did not for:

Formal writing and official statements:
- The defendant did not appear in court.
Emphasis in speech:
- I did not say that! (stressed)
Academic and professional contexts:
- The experiment did not produce expected results.

Grammar Test 2

Do this exercise to test your grammar again. Choose the most appropriate auxiliary verb.

1. The machine work properly since last week.

2. The committee approve the proposal during yesterday's meeting. (formal report)

3. My sister drink coffee in the evening.

4. We receive your email yesterday.

5. The weather look good for our picnic today.

6. The accused confess to the crime during interrogation. (police report)

7. I tell you that secret! (emphatic denial)

8. The new employee know how to use the computer system yet.

9. They show up for the appointment last Tuesday.

10. The research support the initial hypothesis. (academic paper)