MODAL VERBS
A. FUNCTION
1. Can, Could, Be Able To
- Can
Is used to talk about possibility.
Is used to talk about ability.
Is used to make informal requests and orders.
Has two negative forms, is
can’t and
cannot.
- Could
Is used to talk about past abilities.
Is used to make formal requests.
In the negative form, is couldn’t.
- Be Able To
Is sometimes used instead of can or could.
Can be used with all tenses.
Is used to talk about ability.
2. Might and May
- Might
Is used mostly to express possibility.
To make suggestions or requests, although this is more common in British English and could be seen as extremely formal.
Is also used in conditional sentences.
- May
Is mostly used to express possibility.
It can also be used to ask and to give permission although this function is becoming less common.
3. Will and Would
- Will
Is used to show desire, preference, choice or consent.
To show the future.
To express capability.
To express determination or insistence.
- Would
Is used to show preference.
To show a wish.
For advice.
4. Must and Have to
- MustIs mostly used to express certainty however as seen above it can also be used for necessity.
It is also used to express strong obligation.
Most native speakers prefer ‘have to’ which is less restrictive in its meaning.
- Have to
Is used to express certainty, necessity, and obligation.
Is used in the present, past or future.
5. Shall, Should, and Ought To
- Shall
To make a suggestion.
Shall for obligation in very formal situations.
- Should
Should is often used to give an opinion, to make a suggestion, express a preference or an idea.
To ask for an opinion.
B. DIFFERENCE
1. Can, Could, Be Able To
IN THE PRESENT:
“Can” and “able to” are the same in the present tense:
Yes, I can take on this project.
Yes, I‘m able to take on this project.
The negative forms are can’t and am not / is not / are not able to.
IN THE PAST:
We use “could/couldn’t” or “was/wasn’t able to.”
In general, both are used in the negative form:
I wasn’t able to finish all my homework yesterday.
I couldn’t finish all my homework yesterday.
But in the positive form, “was able to” is more common than “could”:
I was able to leave work a little early yesterday.
Don’t say didn’t can in the past – it doesn’t exist, and it’s a common error in English!
IN THE FUTURE:
In the future, there is only one form: “will be able to”:
I have some free time tomorrow, so I‘ll be able to work on this project.
Sorry, I won’t be able to go to the party on Thursday. I have school the next day.
Don’t say “will can” or “won’t can” – it’s another common error in English!
WHEN ASKING SOMEONE TO DO SOMETHING:
When you are asking someone to do something, use “could” (more formal) or “can” (more informal):
Could you bring me a glass of water, please?
Can you bring me a glass of water, please?
WHEN ASKING ABOUT SOMEONE’S ABILITIES:
In this case, you can use either CAN or ABLE TO:
Can you run a mile in less than 10 minutes?
Are you able to run a mile in less than 10 minutes?
Can is probably more common in spoken English, simply because it’s shorter.
2. Might and May
The usages of may and might are similar. Although one or the other is more likely to be used in some contexts, neither choice will be wrong. Below is an introduction to the most important uses of may and might.
3. Will and Would
When to Use Will
What does will mean? Will can be a noun, in which case it has various meanings. In this article, though, I will be concerned with will as a verb.
Will is a modal auxiliary verb, where it describes an action that is expected to take place in the future. It modifies many verbs in their future tenses.
Here are some examples,
You will arrive at the airport at 10:15am Thursday morning and escort the ambassador back to the royal palace.
Catalina will turn us in at the earliest opportunity.
I will sell my car when I can afford to buy a newer one.
Apple Inc. said Wednesday it will open its new campus in April and spend six months moving employees into a glass-encased building reminiscent of a spaceship. –The Wall Street Journal
When to Use Would
What does would mean? Would is another verb with multiple senses. Sometimes, it is the past tense of will but only under certain conditions.
Would describes something that was in the future at the time of the original action, but is no longer in the future now.
Here is an example,
“Jess said she would pick up the pizza,” said Erik.
In this example, Jess made a statement in the past about her intention to pick up a pizza in the near future. However, Erik is now referring to the event from a point even further in the future.
Here is another example,
Nissan said its new chief executive would be Hiroto Saikawa, a 40-year company veteran who had served as Nissan’s “chief competitive officer” and had led its operations in North America. –The New York Times
Would is also a conditional verb. It indicates an action that would happen if certain circumstances were met.
Here is an example,
I would buy a dishwasher if you ever cooked us anything.
4. Must and Have to
Must
We use must to make a logical deduction based on evidence. It indicates that the speaker is certain about something:
Examples:
It has rained all day, it must be very wet outside.
The weather is fantastic in California. It must a lot fun to live there.
Must is also used to express a strong obligation.
Examples:
Students must arrive in class on time.
You must stop when the traffic lights are red.
I must go to bed.
Have to
Like must, have to is used to express strong obligation, but when we use have to there is usually a sense of external obligation. Some external circumstance makes the obligation necessary.
Examples:
I have to send an urgent email.
I have to take this book back to the library.
5. Shall, Should, and Ought To
Difference Between Shall and Should
Key Difference: ‘Shall’, most commonly, refers to something that a person must to or intends to do. While ‘should’ is used as a past tense of ‘shall’.
‘Shall’ and ‘should’ are interrelated words, in the sense the ‘should’ is the past tense of ‘shall’. However, in many cases, ‘should’, being a modal verb acts differently under certain circumstances. Let’s see the definition of each word in order to better understand its behavior and usage.
Dictonary.com defines ‘shall’ as:
Something that will take place or exist in the future
Something, such as an order, promise, requirement, or obligation
The will to do something or have something take place
Something that is inevitable
To be able to
To have to: must
An offer, suggestion or request
From this we can see that the usage of the word shall differs according to the context it is used it. Most commonly, shall is used in order to state something a person must do, or will do.
Examples of Shall:
We shall arrive tomorrow.
You shall leave now.
He shall answer for his misdeeds.
I shall go out if I feel like it.
That day shall come.
You shall do as I say.
Shall we go out for lunch?
‘Should’ on the other hand is commonly considered as a past tense of ‘shall’; however it does not always act as such. ‘Should’ being a modal verb, changes usage depending on the context. A modal verb gives more information about the function of the main verb that it governs.
Dictionary.com defines ‘should’ as:
Simple past tense of shall
Used to express condition
must; ought
would
to express futurity from a point of view in the past
Examples of ‘should’:
If he should leave his father, his father would die
You should brush your teeth after each meal
She realized that she should have to do most of her farm work before sunrise
I should think you would apologize.
You should not do that.
People with high cholesterol should eat low-fat foods.
We should return the video before the video rental store closes.
I should have started on my paper by now
C. EXAMPLE
1. Can, Could, Be Able To
Present and Future:
- Tom can write poetry very well.
- Mike is able to solve complicated math equations
- Lisa can’t speak French.
Past:
- When I was a child I could climb trees.
- He hasn’t been able to get in touch with the client yet.
- I wasn’t able to visit her in the hospital.
Possibility / Impossibility:
- You can catch that train at 10:43.
- He can’t see you right now. He’s in surgery.
- I could fly via Amsterdam if I leave the day before.
Ask Permission / Give Permission:
- Can you lend me ten dollars?
- You can borrow my car.
- Could I have your number?
- Could I talk to your supervisor please?
Formal Permission / Formal Prohibition:
- You may start your exam now.
- You may not wear sandals to work.
Polite Request:
- May I help you?
Possibility / Negative Possibility:
- We may go out dinner tonight. Do you want to join us?
- Our company might get the order if the client agrees to the price.
- Adam and Sue may not buy that house. It’s very expensive.
- They might not buy a house at all.
To Make a Suggestion (when there is no better alternative):
- You may as well come inside. John will be home soon.
- We might as well take Friday off. There’s no work to be done anyway.
Polite Suggestion:
- You might like to try the salmon fillet. It’s our special today.
Polite Request or Statement:
- Will you please take the trash out?
- Would you mind if I sat here?
- I’d (I would) like to sign up for your workshop.
4. Must and Have to
Present and Future:
- You must have a passport to cross the border.
- Elisabeth has to apply for her visa by March 10th.
Past:
- I had to work late last night.
Almost 100% Certain
- Thomas has lived in Paris for years. His French must be very good.
To Persuade
- You must try this wine. It’s excellent.
- You have to visit us while you’re in town.
Prohibited or Forbidden
- You must not drive over the speed limit.
- You mustn’t leave medicines where children can get to them.
Lack of Necessity
- You don’t have to park the car. The hotel valet will do it for you.
- Tim doesn’t have to go to school today. It’s a holiday.
- You didn’t have to shout. Everyone could hear you.
5. Shall, Should, and Ought To
To Offer of Assistance or Polite Suggestion (When you are quite sure of a positive answer)
- Shall we go for a walk?
Note: Shall is only used with I or we. It is used instead of will only in formal English.
To Offer of Assistance or Polite Suggestion (When you are not sure of a positive answer)
- Should I call a doctor?
A Prediction or Expectation that Something Will Happen
- The proposal should be finished on time.
- I shouldn’t be late. The train usually arrives on time.
To Give Advice
- You should check that document before you send it out.
- You ought to have your car serviced before the winter.
To Give Advice (about something you think wrong or unacceptable)
- James shouldn’t teach him words like those.
REFERENCE
http://www.ecenglish.com
http://www.gingersoftware.com
