Modal auxiliary verbs are the verbs that help other verbs to express doubt, certainty, possibility, probability, permission, necessity/obligation, and ability.
These verbs include can, could, may, might, will, would, shall, should, must, ought to, dare, need not …
The following is the difference between primary auxiliary verbs and modal auxiliary verbs:
Primary auxiliary verbs
-They can be used as main verbs
-They change their forms
-We can have more than one primary aux. verb in a sentence
Examples: be, have, do
Modal auxiliary verbs
-They must be used with other verbs.
-They do not change their forms.
-We cannot have more than one modal verb in a sentence.
Examples: can, may, must…
It is used for:
- Making predictions
I think the colour will change.
We know he will win the elections.
Note: When we use “will” to express future events, we are making predictions.
- Expressing certainty.
The principal will not be in the office.
I am sure you will understand him.
- Reassuring someone, making a decision.
It will be alright.
I am very tired. I will not go anywhere
- Expressing an offer to do something, a premise or a threat.
I will pay for lunch. (offer)
Don’t worry; I will be there. (promise)
If you don’t do your assignment, your will be punished by the teacher. (threat)
- Making a request.
Will you please pass the message to the mayor?
Who will help me to clean the class?
- Expressing orders and rules.
All students will attend the assembly.
You will not see him without my permission.
It is mostly used in the first person; however, its use is not very common.
It is used for:
- Making offers.
Shall I get you a cup of tea?
Shall we open the window?
- Making suggestions or asking for advice.
Shall we go to the stadium?
What shall we do? The baby’s temperature is high.
- Saying what must be done.
You shall keep all your books out of the class during the examinations.
They are used to talk about possibilities in the present, past, and future. However, may is sometimes used when one is a bit more sure, while might expresses some doubt.
They are used:
- To show possibility.
Claude may be in the staffroom.
Martin might win the cross-country race.
- To ask to be allowed to do something or saying that something is allowed.
I wonder if I might use your car.
You may go to watch the play tomorrow.
- To express polite offers, requests, or suggestions.
I had hoped we might have dinner soon.
May I take a photograph of your baby?
- To express a wish.
May God bless you.
May you have a wonderful day.
May good sense and fairness prevail.
- To express permission in a formal and a more polite way.
May I use the bathroom?
Please teacher, may I go out?
Note: For the past, we use “may have + past participle” or “might + have past participle”
She may have been asleep. (perhaps she was asleep)
You might have left it at work. (perhaps you left it at work)
It is used for:
- Making polite requests and offers.
Would you like some sugar?
Would you please call him for me?
- Offering advice or suggestions.
If I were you, I would be very nice.
I would rather talk to the teacher first.
- Expressing other’s willingness.
He would forgive you if you showed remorse.
Is it true that a lion would eat grass if it is very hungry?
- Talking about outcomes.
What would happen if a market caught fire?
I would have forgiven her if she had shown remorse.
- Talking about past habits.
Examples: When I lived in Uganda, I would always visit Kenya in December.
- Making reported speech when we have “will”.
“The meeting will start tomorrow”, he said. (direct speech)
He said that the meeting would start the next day. (reported speech)
- Imagining a situation or action.
It would be nice to buy a new car, but we can’t afford it.
I wouldn’t like to live by the sea.
Note: In the past, we use “would have + past participle” when we imagine situations or things that didn’t happen.
Kalisa would have paid the school fees, but he hadn’t been informed.
They are used in the following ways.
- To talk about ability, making requests, and ask questions.
Can you lift the bag? (ability)
Anitha can swim in the lake. (ability)
Could you close the door, please? (request)
Could I visit Stella this afternoon? (permission)
- In reported speech, could is used in places where direct speech has used can.
“Can you speak up?” he asked. (direct speech)
He asked her if she could speak up. (reported speech)
- To express present, past, and future possibilities.
My father thinks you could be right.
If I had known it, I could have stayed at home.
When I go to the market, I suppose I could buy some vegetables.
- To say what sometimes happens.
Throat infections can cause heart problems.
Temperatures here can rise to 400C.
- To say that something is possible or allowed.
You don’t have a pen. You can use mine.
The word ‘dream’ can be a verb or a noun.
Note: The negative form of can is cannot (can’t)
Can = be able to
Examples: You can see the lake from the hotel.
You are able to see the lake from the hotel.
It is used to express:
- Necessity and obligation.
Every student must work hard.
We don’t have much time. We must hurry.
You must keep it a secret. You mustn’t tell anyone.
We must be very quiet. We must not make any noise.
- Strong advice and invitations.
I think you must read all the set books. (advice)
You must watch the play. It is very interesting. (invitation)
- Something that is certain.
This must be his car. I recognize the registration number.
Note: The past form of ‘must’ is ‘had to’.
Examples: They must do that work. = They had to do that work.
It is used:
- To give advice, express obligation.
You should read the instructions carefully. (advice)
Children should obey their parents. (obligation)
The visitor should be here any time now.
You shouldn’t believe everything you read in newspapers.
- To express things that did not happen or may/may not have happened.
I should have taken medicine today, but I forgot.
Mary should not have left so early.
You should have done something about the problem.
You went to bed late last night. You should have gone to bed earlier.
- OUGHT TO
‘Ought to’ has the same meaning as ‘should’ when talking about something that should happen/has happened.
You ought to respect elders. (you should respect elders)
He ought to have been polite to the visitors. (he should have been polite…)
Jack ought not to go to school so late. (Jack should not go …)
Ought I cross the road right now? (Should I cross the road ….?)
- NEED/NEED NOT
‘Need’ is used to express necessity while ‘need not‘ is used to remove necessity. This modal verb is not commonly used in affirmative sentences.
Need I tell you everything?
They need not accompany me.
You need not go away from your family without permission.
Need she change her plans?
The past form of ‘need not’ is ‘needed not’
I need not dance with her. I needed not dance with her.
He need not read the magazine. He needed not read the magazine.
Dare means “have the courage to do something’’. As a modal verb, it is used in negative and interrogative sentences.
I daren’t think how many they are.
How dare she criticize us?
Dare he fight?
You dare not do that.
Musoni dare not insult his parents.