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Grammar Exercises

Auxiliary Verbs: Be, Have, Do, Modals + 30 Exercises

An auxiliary verb (also called a helping verb) is a verb that works with a main verb to add grammatical meaning such as tense, voice, mood, or negation. In “She is writing,” is is the auxiliary and writing is the main verb; in “They have left,” have helps form the present perfect.

Written by Raheel AshrafAbout 14 min read

Free practice: Free English grammar exercises online (with answers)

An auxiliary verb, or helping verb, comes before a main verb and adds grammatical information: time and aspect (She is working, They have finished), voice (It was built), questions and negatives (Do you agree? I don’t), or attitudes like ability, permission, and obligation (can, may, must). English has three primary auxiliaries — be, have, and do — and nine core modal auxiliaries: can, could, may, might, must, shall, should, will, and would.

Be, have, and do can also be main verbs (I have a car; She does the dishes), so the same word can be an auxiliary in one sentence and a main verb in the next. The 30 exercises below cover all of this, plus do-support, short answers, and tag questions, with instant answers and explanations.

Auxiliary Verbs Quiz: 30 Questions

Warm-up · find the auxiliary

1.Which word is the auxiliary verb? “She is writing a report.”
2.Which word is the auxiliary verb? “They have finished the project.”
3.In “I have two brothers,” what is have?
4.Fill in: ___ you like coffee?
5.Fill in: She ___ not want to go.
6.Fill in: The letters ___ delivered yesterday.
7.Which of these is a modal auxiliary?
8.Fill in: He ___ swim when he was five.
9.Short answer: “Have you met Sarah?” — “Yes, I ___.”
10.Tag question: “You’re coming tonight, ___?”

Core · do-support, modals, contractions

11.Choose the correct question.
12.Choose the correct negative.
13.Choose the correct sentence with can.
14.Fill in: ___ she called you yet?
15.Which sentence uses do for emphasis?
16.In “I do my homework after dinner,” what is do?
17.Fill in: You ___ wear a seatbelt — it’s the law.
18.What does might express in “She might be late”?
19.Which is the correct short answer to “Does he work here?”
20.In “She’s been to Paris,” what does ’s stand for?

Challenge · tags, combinations, main vs auxiliary

21.Tag question: “She has finished, ___?”
22.Tag question: “He has a car, ___?”
23.Choose the correct past-tense question.
24.Which sentence contains both a modal and a primary auxiliary?
25.In which sentence is be a main verb, not an auxiliary?
26.Which of these is a semi-modal?
27.Fill in: ___ I open the window? (a polite offer)
28.Choose the correct sentence with need.
29.Where does not go in a sentence with an auxiliary?
30.Why is “Who called you?” correct without do?
Answer key and explanationsOpen after you finish the quiz.
  1. 1. isIs helps the main verb writing form the present continuous. Be + -ing is the continuous pattern, and the auxiliary carries the tense and agrees with the subject (she is, they are).
  2. 2. haveHave + past participle forms the present perfect, so have is the auxiliary and finished is the main verb. The auxiliary is the part that changes for tense: they had finished.
  3. 3. A main verbHere have means possess and is the only verb in the sentence, so it is a main verb. It is an auxiliary only when it helps another verb, as in I have met them.
  4. 4. DoPresent simple questions with a main verb need the auxiliary do: Do you like coffee? Be and have are not used to form questions with like in modern English.
  5. 5. doesPresent simple negatives use do + not + base verb, and do takes the -s ending for she: She does not want. The main verb stays in the base form (want, not wants).
  6. 6. wereThe passive uses be + past participle, and yesterday calls for the past tense: The letters were delivered. Did cannot combine with a past participle, and had delivered would need the letters to be the ones delivering.
  7. 7. shouldShould is a modal: it has no -s form (she should), is followed by a bare infinitive (should go), and forms questions and negatives without do. Seem, become, and get are ordinary verbs.
  8. 8. couldCould is the past form of can for general ability: He could swim when he was five. Can is present, and is able would need to and a past form: was able to swim.
  9. 9. haveA short answer repeats the auxiliary from the question: Have you…? — Yes, I have. Using do, am, or the main verb met breaks the pattern.
  10. 10. aren’t youA tag question repeats the auxiliary of the main clause with the opposite polarity: You are coming → aren’t you? The subject pronoun matches too (you, not it).
  11. 11. Where do you work?Wh-questions in the present simple need do before the subject: Where do you work? Does is only for he, she, and it, and the auxiliary must come before the subject, not after it.
  12. 12. He doesn’t like spinach.The -s marks tense and person only once, on the auxiliary: doesn’t + base form like. He don’t is nonstandard, and He doesn’t likes doubles the -s.
  13. 13. She can drive.Modals never take -s and are followed by the bare infinitive, without to: She can drive. This holds for all nine core modals (must go, should ask, will be).
  14. 14. HasCalled after the subject is a past participle, which pairs with have to make the present perfect: Has she called you yet? Did and does need a base form (Did she call…?).
  15. 15. I do like your new haircut.In a positive statement, stressed do before a base verb adds emphasis: I do like it. In the first sentence do is the main verb, and in the second it forms a question.
  16. 16. A main verbDo is the only verb in the sentence and means perform, so it is a main verb. Its negative even needs auxiliary do as well: I don’t do my homework after dinner.
  17. 17. mustIt’s the law signals obligation, which must expresses. Might and could express possibility or options, which does not fit a legal requirement.
  18. 18. PossibilityMight expresses possibility: it is possible she will be late. Obligation would be must or have to, ability can or could, and permission may or can.
  19. 19. Yes, he does.Short answers reuse the auxiliary from the question in the right form: Does he…? — Yes, he does. He is and he has switch to a different auxiliary, and he do breaks subject-verb agreement.
  20. 20. hasBeen is a past participle, so the auxiliary must be have: She has been to Paris. In She’s working, by contrast, ’s stands for is, because -ing follows.
  21. 21. hasn’t sheHas is the auxiliary in has finished, so the tag repeats it in the negative: hasn’t she? Tags copy the first auxiliary; they only use do when the clause has no auxiliary.
  22. 22. doesn’t heHere has is a main verb, so the tag uses do-support: He has a car, doesn’t he? (British speakers may also say hasn’t he.) Is and was do not match the verb at all.
  23. 23. Did she go home early?Did carries the past tense, so the main verb returns to the base form: Did she go? Marking the past twice (did + went) is a common error, and inverting the main verb is archaic.
  24. 24. She should have called.Should (modal) + have (primary auxiliary) + called (main verb). When auxiliaries stack, the modal always comes first, then have, then be: should have been calling.
  25. 25. They are tired.In They are tired, are is the only verb and links they to an adjective, so it is a main (linking) verb. In the others it helps sleeping (continuous) and invited (passive).
  26. 26. have toHave to behaves like a modal in meaning (obligation) but like an ordinary verb in grammar: she has to, does she have to? Must, shall, and will are core modals.
  27. 27. ShallShall I…? is the standard formula for offers and suggestions with I or we. Must I asks about obligation, Do I asks for instructions, and Will I asks about the future.
  28. 28. You don’t need to come.Need works two ways: as an ordinary verb with do and to (don’t need to come), or as a modal with a bare infinitive (needn’t come). Mixing the two patterns is wrong.
  29. 29. She has not finished.Not goes directly after the first auxiliary: She has not (hasn’t) finished. If there is no auxiliary, you add do to carry it: She did not finish.
  30. 30. Because who is the subject of the questionWhen the question word is the subject, there is no inversion and no do: Who called you? Compare the object question Who did you call?, where do-support is required.

The Primary Auxiliaries: Be, Have, Do

Each primary auxiliary has its own grammatical job. They change form for tense and person (is/was, has/had, does/did), and the first auxiliary in a verb phrase is the one that carries tense.

  • Be + -ing = continuous: She is working; They were waiting.
  • Be + past participle = passive: The bridge was built in 1932; Mistakes were made.
  • Have + past participle = perfect: I have finished; She had already left.
  • Do + base verb = questions, negatives, and emphasis in the simple present and past: Do you know? I didn’t see it. I do agree.
  • They combine in a fixed order: have + be + -ing (has been working), be + being + participle (is being repaired).

Only the first verb in the chain changes for tense and person: she has been working, not she have is working.

Auxiliary or Main Verb? Be, Have, and Do Do Both

Be, have, and do are auxiliaries when another verb follows them in the same verb phrase. When they are the only verb, they are main verbs with their own meaning.

  • be: She is happy (main, linking) / She is laughing (auxiliary).
  • have: I have a meeting (main, possess) / I have finished (auxiliary).
  • do: He does the accounts (main, perform) / He doesn’t know (auxiliary).
  • Both at once: I didn’t do it — did is the auxiliary, do is the main verb.
  • Main-verb have usually takes do-support: Do you have a pen? (Have you got a pen? is the British alternative.)

The Do-Support Rule

English forms questions and negatives by moving or adding to an auxiliary. If the sentence already has one (is, have, can, will…), you use it: Can you swim? She isn’t here. If it has no auxiliary — a present simple or past simple main verb — you add do, which takes over the tense, and the main verb returns to its base form.

  • She works → Does she work? / She doesn’t work.
  • They left → Did they leave? / They didn’t leave.
  • No do-support with be as a main verb: Is she ready? (not Does she be ready?)
  • No do-support in subject questions: Who wrote this? (not Who did write this?, unless stressed)
  • Do for emphasis or contrast: I did lock the door — I’m sure.

Tense goes on the auxiliary once: Did she go? — never Did she went?

Contractions, Short Answers, and Tag Questions

Auxiliaries carry the weight in conversation. They contract with subjects and with not, they stand alone in short answers, and they form the tag at the end of a question.

  • Contractions: I’m, you’re, she’s (is or has), we’ve, they’d (had or would), I’ll; isn’t, hasn’t, doesn’t, can’t, won’t, shouldn’t.
  • Short answers repeat the auxiliary: Are you ready? — Yes, I am. Can she come? — No, she can’t.
  • Tag questions reverse polarity: It’s cold, isn’t it? You haven’t eaten, have you?
  • No auxiliary in the clause? The tag uses do: You live here, don’t you?
  • Special cases: I’m right, aren’t I? Let’s go, shall we?

Don’t contract in a positive short answer: Yes, I am (not Yes, I’m) and Yes, she has (not Yes, she’s).

Keep practicing

Frequently Asked Questions

What are auxiliary verbs?

Auxiliary verbs, also called helping verbs, are verbs that come before a main verb to add grammatical meaning such as tense, voice, questions, negation, or modality. The primary auxiliaries are be, have, and do; the modal auxiliaries are can, could, may, might, must, shall, should, will, and would.

What is the difference between an auxiliary verb and a main verb?

A main verb carries the core meaning (eat, write, decide); an auxiliary helps it (is eating, has written, didn’t decide). Be, have, and do can be either: in I have a car, have is a main verb; in I have bought a car, it is an auxiliary.

How many auxiliary verbs are there in English?

There are three primary auxiliaries (be, have, do) and nine core modal auxiliaries (can, could, may, might, must, shall, should, will, would). Grammars also list semi-modals such as have to, need to, ought to, and be going to, so exact totals vary by source.

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Sources & References

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