Auxiliary Verbs
Mastering Auxiliary Verbs
A Comprehensive Guide to Helping Verbs, Modals of Ability, Permission, Obligation, Advice, and Phrasal Verbs
What Are Auxiliary Verbs?
Auxiliary, or helping verbs, are placed before base infinitive verbs to alter or expand their meaning. They allow speakers and writers to specify whether someone is able to do something, allowed to do something, or obligated to do something.
1. Can and Could
The modals can and could express physical or mental ability, permission, requests, offers, and suggestions.
A. Expressing Ability
Use can for present ability and could as the simple past tense of can:
- She can draw really good pictures.
- Philip can run faster than Matt.
- She could already read before she started school.
- I ran as fast as I could.
B. Asking and Giving Permission
- My mom says you can come to our house for dinner.
- Our teacher said we could go home early.
- The big sign on the gate said PRIVATE, so we couldn't go in.
C. Inquiries, Offers, and Polite Suggestions
- Inquiries: Can you tell me if this train goes to Topeka? / Could you open that window, please?
- Offers: You can borrow my pen, if you like. / I could lend you my football.
- Suggestions: We can go to the library instead. / You could ask your dad to help us.
• When adding not to can, write it as a single word: cannot (never can not).
• Negative contractions: cannot → can't; could not → couldn't.
2. Will and Would
The auxiliaries will and would are used to make requests, extend invitations, offer help, and present polite choices.
A. Making Direct or Polite Requests
- Will you please stop making that noise?
- Would you pass me that book, please?
- Please, will you close the door?
B. Offers and Polite Inquiries
- Will I hold this end of the rope?
- Will I carry the bag for you?
- Would you like another drink?
- Which cake would you like?
• will not → won't (e.g., "Won't you stay and eat with us?")
• would not → wouldn't (e.g., "Wouldn't it be better to wait?")
3. Shall and Should
The helping verbs shall and should are utilized to seek advice, extend offers, and provide recommendations.
A. Seeking Advice and Offering Help
- Should I bring waterproof clothes?
- Should I phone the police?
- Shall I help you with that heavy bag?
- Shall we go home now?
- Shall I go by car, or will it be better to walk?
B. Making Recommendations
Use should to offer constructive advice or counsel:
- You should try that new French restaurant.
- They should stop making all that noise.
- You should think more about other people and less about yourself.
4. Ought To and Must (Duty, Obligation & Rules)
A. Ought To: Duty and Strong Suggestions
The auxiliary ought to conveys moral duty, correctness, and strong suggestions:
- You look tired. You ought to go to bed early tonight.
- I ought to get more physical exercise.
- We ought to lock the door when we leave home.
- You ought to turn off the computer when you're not using it.
- Negative Form: You ought not to believe everything you see on television.
B. Must: Mandatory Requirement and Necessity
Use must for essential requirements and rules that cannot be bypassed:
- I must mail this letter today.
- You must speak louder. I can't hear you.
- You must stop at the curb and look before you cross the street.
- Children must listen to the teacher if they want to learn.
• Must retains the exact same form in past contexts.
• Must Not (Mustn't) indicates strict prohibition: "Children must not play with matches"; "Drivers mustn't park their cars in the middle of the road."
5. May and Might (Permission & Possibility)
A. Formal Permission
Use may in formal contexts to ask for, grant, or deny permission:
- "May I go out to play now?" — "Yes, you may."
- May I borrow your pen?
- John may leave now, but Sally may not.
B. Possibility and Likelihood
Both may and might express uncertain outcomes or potential future events:
- Take an umbrella. It might rain.
- I may not have time to go swimming tonight.
- If you're not careful, you may hurt yourself.
- "Are you going to the concert?" — "I don't know. I might or I might not."
6. Auxiliary Verb Function Matrix
Quick-reference guide to select the right helping verb for every grammatical context:
| Grammatical Function | Primary Auxiliaries | Sample Sentence |
|---|---|---|
| Physical / Mental Ability | can, could | Philip can run faster than Matt. |
| Informal Permission | can, could | Mom said I could have ice cream. |
| Formal Permission | may | May I see your ticket, please? |
| Polite Requests & Inquiries | would, will, could | Would you pass me that book, please? |
| Advice & Moral Duty | should, ought to | You ought to turn off the computer. |
| Compulsion & Obligation | must | You must mail this letter today. |
| Possibility & Likelihood | may, might | Take an umbrella. It might rain. |
7. Verb Phrases (Phrasal Verbs)
A verb phrase consists of a base verb combined with one or two prepositions (such as after, into, over, out of). The attached preposition produces an idiomatic meaning distinct from the standalone verb.
Two-Part Verb Phrases
| Phrasal Verb | Idiomatic Meaning | Example Sentence |
|---|---|---|
| look after | take care of | Who looks after the baby when parents work? |
| take after | resemble in appearance/character | Mike takes after his mother. |
| bump into | meet unexpectedly / by chance | Dad bumped into an old friend at the station. |
| get into | become interested in | My sister is getting into pop music. |
| get over | recover from an illness | Is your mom getting over her illness? |
| look over | inspect or examine | Inspectors came to look over the factory. |
Three-Part Verb Phrases
Some phrasal combinations incorporate two prepositions:
- get away with: escape punishment for a wrongdoing → We hoped that the thieves wouldn't get away with their crime.
- run out of: exhaust a supply completely → I am going to the store because we have run out of rice.
Quick Check: Test Your Knowledge
1. Negative Modal Construction:
Rewrite correctly: "They (can not / cannot) find their way back to the hotel."
→ Correct Form: cannot (written as a single unified word).
2. Obligation vs. Advice:
"You look sick and exhausted. You (must / ought to) go to bed early tonight."
→ Answer: ought to (strong advice/suggestion, rather than a strict legal command).
3. Phrasal Verb Meaning:
What does "run out of" mean in: "We have run out of milk"?
→ Answer: Used all our supply of it.