Tag: modals

Level: Intermediate-Advanced

Modal verbs for deduction are used when trying to see whether something is true or not. The way we choose these modal verbs is an indication of how big we think the possibility is. Some modals of deductions about the past are must have, might have/may have, and can’t have/couldn’t have.

Compare:

She must be really exhausted from working all day. (present deduction)
She must have been very exhaused when she had to work all day. (past deduction)

must have

Must have + past participle is used to express certainty about something.

She couldn’t find her purse. She must have left it at the restaurant.
Allan must have had the flu. He didn’t show up at any of his appointments today.
We’ve got enough money. Michelle must have saved on her meal earlier.

might have / may have

Might have or may have + past participle is used to express the possibility that something happened.

I might have bought the wrong brand. Can you please ask Mom to check?
Joe thinks his wife may have left with her lover.

Note: Might have is the less formal form compared to may have. Could have is another possible form to be used in such context but it is not that very common.

can’t have / couldn’t have

Can’t have and couldn’t have + past participle are used to express that it is not possible for something to happen.

They can’t have left the party yet because their car is still outside.
Andrea thought she saw her old university professor this morning but it couldn’t have been her – she moved abroad years ago.

Level: Beginner-Intermediate

We use CAN to make general statements about what is possible:
Example:
It can be very hot here in summer. (= It is sometimes very hot here in summer.)
You can easily get lost in this city. (= People often get lost in this city.)

We also use CAN and CAN’T to talk about someone’s skill or general abilities:
Example:
He can speak two languages.
She can dance.
She can’t swim very well.

We use COULD to show that something is possible, but not certain:
Example:
They could come by bus. (= Maybe they will come by bus.)
They could be at school. (= Maybe they are at school.)

We also use COULD to mean that we were able to do something in the past.
Example:
When she was 1, she could talk.

We use COULDN’T to mean that we weren’t able to do something in the past.
Example:
When he was 1, he couldn’t walk.

CAN

-Used to say that something is possible or allowed

Example:
I can meet you later if you want.
I can go out this weekend as long as I finish my housework.

-Used to say that someone has the ability to do something

Example:
He can speak seven languages.
She can solve math problems in 30 seconds.

The negative form of CAN is CAN NOT (contraction: can’t).

Example:
I’m afraid I can’t go to the theater with you on Friday.

-You use CAN’T to say that you believe something is not possible

Example:
You’ve just had dinner. You can’t be hungry already.

COULD 

-Sometimes could is the past tense of CAN

We use could especially with:
Hear, smell, taste, feel, see, understand,remember

Example:
As soon as I got in my room, I could smell the burning air conditioner.

-Is also used to say that somebody had the general ability to do something

Example:
She could dance well when she was in her teens.

-Is also used to say someone had permission to do something

Example:
We could go out at night. My grandparents weren’t too strict with us.

The negative form of could is COULD NOT (contraction: COULDN’T).

-Used to talk about possible actions NOW or in the future (especially to give suggestions)

Example:
You could stay in my house when you go to Paris.

-Used for actions that are not realistic

Example:
I am so hungry, I could eat a cow.

-We also use could to say that something is possible now or in the future. (similar to might in meaning)

Example:
She could be waiting for you at the hotel.

This lesson focuses on modals will, may, might. To form, simply combine the modal and present participle.

May and Might

The modals may and might are used when expressing what might occur in the future. Both can be used to express actions in the future or the present.

Present

I might have some flour in the pantry.

Future

They may leave tomorrow.

May and might function as modals such as can, will and should. Therefore, the same rules apply.

• No need to add ‘s’ to the third person singular.

Correct: He may attend.

Incorrect: He mays attend.

Correct: She might cry.

Incorrect: She mights cry.

• The negative form is: may / might + not.

He may not attend the meeting.

She might not buy the book.

• The question form is: may / might + subject. However, using might in forming questions is not very common.

Might she be hungry?

• To make requests, May can be used with ‘I’ or ‘we’. However, it is more common to use can and could.

May I have some water?

May we eat the sandwiches?

• The modals may and might are always followed by the infinitive form of the verbs.

Correct: I might sing.

Incorrect: I might to sing.

Correct: She might stay.

Incorrect: She might staying.

Will + Probability Adverbs

You can combine will and won’t and some adverbs to express the probability of a future event happening.

I’ll possibly cook something for dinner.

You’ll probably cook something for dinner.

She’ll definitely cook something for dinner

He’ll certainly cook something for dinner.

• Remember that Will / ‘ll comes before the adverb and won’t comes after.

I’ll probably watch a movie later.

I probably won’t watch a movie later.

Will May Might Modals Exercise

Answer this exercise on will, may, might modals.

1. ______ I go to your house tonight?

a. Might

b. May

2. _____ some cookies later.

a. I’ll probably bake

b. I’ll bake probably

3. They ______ to their friends’ advice.

a. probably won’t listen

b. won’t listen probably

4. I don’t know where your socks are. They _____ in the drawer.

a. might be

b. may be

5. She ______ her baby.

a. will certainly look after

b. certainly won’t look after

6. _____ I have your attention, please?

a. May

b. Might

7. I ______ the meeting on Thursday.

a. may attend

b. might attend

8. You _____ without me. It’s okay.

a. may start

b. will possibly start

9. Students ______ for free.

a. might study

b. may study

10. The team _____ overtime today.

a. will probably work

b. may work

Find the answers to this exercise here.

See also: Modals of Deduction and Speculation and Modals Continuous: Past and Present

For additional information on this topic, check out this British Council lesson.

For other English grammar lessons, go to this page.

This lesson focuses on the needn’t have and can’t have modals. To form, simply combine the negative modal, have, and the past participle.

Form

needn’t or can’t have + past participle

Can’t Have + Past Participle

• Use this when we are definitely sure that something did not happen in the past or we believe that something was impossible in the past.

Her car is still in the garage. She can’t have left the house yet.

He can’t have escaped through this window – it’s too small.

He can’t have been at the meeting. He’s on a business trip this week.

Needn’t Have + Past Participle

• Use this to mean that the action is done, but it was unnecessary and even a waste of time.

Yesterday my friend had already bought two tickets for the concert so you really needn’t have bought another one, it was a waste of money.

Martha worked all the weekend to finish her assignment on time, but actually she needn’t have done so.

The bus arrived two minutes after you left, so you needn’t have taken a taxi.

Needn’t Have and Can’t Have Modals Exercise

Answer this exercise on needn’t and can’t have modals.

1. You _____ cleaned your room. The housekeeping would’ve tidied it up for you.

a. can’t have

b. needn’t have

2. They _____ left the country because their children are still in the middle of their school year.

a. can’t have

b. needn’t have 

3. We _____ rehearsed that intensely. The competition is canceled.

a. can’t have

b. needn’t have

4. I didn’t rain so you ______ brought an umbrella.

a. can’t have

b. needn’t have

5. She is very polite. She _____ spoken to her manager in a rude manner.

a. can’t have

b. needn’t have 

6. We had a lot of food in the fridge so we _____ gone to the supermarket today.

a. can’t have

b. needn’t have

7. You _____ seen that movie. It isn’t released until next month.

a. can’t have

b. needn’t have 

8. You _____ bought all these presents for her. She doesn’t feel like celebrating her birthday this year.

a. can’t have

b. needn’t have

9. I _____ taken this medicine. I’m allergic to it.

a. can’t have

b. needn’t have 

10. He ______ seen her in town. She left for the US last month.

a. can’t have

b. needn’t have 

Find the answers to this exercise here.

See also: Modals of Deduction and Speculation and Modals: Will, May, Might

For additional information on this topic, check out this BBC Learning English lesson.

For other English grammar lessons, go to this page.

Use modals of deduction and speculation when we want to make a guess about something. We choose the verb depending on how sure we are.

Deducing and speculating about the present

Combine modals of deduction and speculation must, might, could, may and then an infinitive verb to deduce and speculate about an action that happens in the present.

modal (present) + infinitive

Below is a sample scenario using modals of deduction and speculation in present. Know the proper modal to use depending on how true you think that an action occurs.

You are waiting for Amanda with another friend,  Danny.
You ask Danny this question: Where is Amanda?
Danny speculates:

She must be on her way here. (fairly sure this is a good guess)

She might arrive soon. (maybe)

She could be lost. (maybe)

She may be in the wrong place. (maybe)

She can’t be at home. (fairly sure this isn’t true)

Note that in this case, the opposite of ‘must’ is ‘can’t’.

Will / won’t

• We use will and won’t when we are very sure.

He will be at school now.

Should / shouldn’t

• We use should and shouldn’t to make an assumption about what is probably true, if everything is as we expect.

They should get there by now.

It shouldn’t take long to drive here.

• This use of should isn’t usually used for negative events. Instead, it’s a better idea to use will.

Correct: The temperature will be too high today.

Incorrect: The temperature should be too high today.

Can

• We use can for something that is generally possible, something we know sometimes happens.

The cost of living can be very high in big cities.

• We do not use can to talk about specific possibilities.

Correct: Mom could be at the supermarket.

Incorrect: Mom can be at the supermarket.

Deducing and speculating about the past

Put together modals of deduction and speculation must, might, could, may, can’t and have and then a past participle verb to deduce and speculate about an action that occurred in the past.

modal (past) + have + past participle

It must have rained last night.

She might / might not have registered for the seminar.

They could have finished the training if not for the technical issues.

You may / may not have done the dishes this morning.

I can’t have wished ill of another person.

Below is a sample scenario using modals of deduction and speculation in the past. Know the proper modal to use.

Roy asked: Where was Sandra last night?
Maria speculated:

Sandra must have forgotten about our appointment.

She might have worked late.

Sandra could have lost track of time.

She may have gotten sick.

She can’t have stayed at home.

Will

• We use will for something in the past that we are very certain happened.

The parcel will have arrived before now.

Should / Shouldn’t

• We use should and shouldn’t have to make an assumption about something that has probably happened, if everything is as we expect.

The plane should have left by now.

We shouldn’t have gone in that direction.

Could

• We can use could + infinitive to talk about a general possibility in the past.

Labor could be low in the sixteenth century.

• This is not used to talk about specific possibilities in the past. Instead, we use could + have + past participle.

He could have been working late.

(not: ‘could be’. As this is a specific possibility, ‘could be’ is present tense)

Modals of Deduction and Speculation Exercise

Answer this exercise on modals of deduction and speculation.

1. Their shop is easy to locate. It’s right around the corner.  She _____ miss it!

a. might

b. can’t 

c. must

2. Chris’s things are still here so he _____ gone home.

a. shouldn’t have

b. might have

c. can’t have

3. What a great show! They _____ go on a world tour.

a. can’t 

b. might

c. must

4. She can’t remember the suspect’s face. But she _____ seen a distinguishing feature.

a. couldn’t have

b. must have

c. may have

5. It _____ be sugar-free. It has ice cream in it.

a. can’t

b. may not

c. must

6. Clara and Laura weren’t replying to my chat messages. Maybe they went to the movies or they _____ gone to a spa.

a. might have

b. couldn’t have

c. must have

7. Anthony is very stressed out lately. I am not sure but he _____ gone on vacation.

a. can’t have

b. might have

c. must have

8. Your sisters tell different versions of what happened. One of them _____ be lying.

a. must

b. may

c. could

Find the answers to this exercise here.

See also: Modals Continuous and Modals: Might, May, Will, Probably.

For additional information on this topic, check out this British Council lesson.

For other English grammar lessons, go to this page.