Modals and Adverbs of Probability

To talk about probability in English, you should learn some of the adverbs of probability. Adverbs of probability are used to show how sure we are about a situation or event.

Let's learn some of the most common ones!

Modal verbs are quite common in English; you’ve seen them in action hundreds of times even if you didn’t know what they were called. Common examples of modal verbs include can, should, and must.

Because they’re a type of auxiliary verb (helper verb), they’re used alongside the infinitive form of the main verb of a sentence.

Can you drive me to the airport?
You should try the lasagna.

The modal verb can expresses whether the subject of a sentence is able to do something. Likewise, the negative form can’t shows that the subject is unable to do something.

She can speak three languages.
I can't cook very well.

CAN and CAN'T also show request, permission, and possibility.

Can or be able to?

Both can and be able to have the same meaning. They are used to talk about ability. But can is used to talk about general ability, and be able to is used to talk about specific ability. In some cases they are interchangeable.

For example: I can swim. (in general) but I'm not able to swim today.

The negative form of to be able to is to be unable to, for example: She nodded, unable to speak.

Be able to is sometimes used after modals such as might or should, and after verbs such as want, hope, or expect.

The modal verbs can and will have special past tense forms:
can → could
will → would

After could or would, we always use the base form of the main verb (the infinitive without to). Would is used for past habits.

Examples:
I could do a handstand when I was a kid. (= I had the ability in the past)
During exam season in college, I would not sleep much. (= this was my habit in the past)

Would and could for politeness

We use could to make polite requests or suggestions (more polite than can).
Could you help me, please?
I could lend you some money if you need it.

We use would for polite offers or to sound less direct.
I would like a coffee. (= more polite than I want a coffee.)
Would you like to join us?

Use may and might to talk about what will possibly happen in the future. May and might mean maybe will. They can refer to the future or the present.

Examples:

I might have a pen in my bag. ( = present use)
She may arrive tomorrow. ( = future use)

May and might are modal verbs like can, will, and should, so they follow the same rules.

1) Do not add -s to the third person singular.
2) To form a negative, add not after may and might.
3) May can be used with I or we to make requests.
4) May and might are always followed by a verb in the infinitive form.

Might and may can also be used to guess what happened in the past.

Form: might/ may/ may not have/ might not have + past participle verb
I might have seen him before. (= I’m not sure, but it’s possible)
He might not have received the message. (= Maybe he didn’t receive it)

When you talk about something in the past that might have happened and you are almost certain that your guess is correct, use must have + past participle verb.

It must have been him!

When you talk about something that didn't happen in the past and you are almost sure about it, use couldn't/ can't have + past participle verb.

He couldn't have forgotten about it!

You already know that modal verbs show possibility, intent, ability, or necessity.

Let's take a look at some modals that can be used to give recommendations.

Must can be used to give a strong recommendation.
You can also use have to for recommendations, but must is more common. ( Have to is generally used to talk about rules and things beyond your control.)
Should and ought to are used to give a suggestion.
Could is used to give an option.
Don’t have to is used to say that something isn’t necessary.
Shouldn't is used to warn someone gently against doing something.
Mustn’t is used to warn someone strongly against doing something.

Should have can be used to express regret about the past – to wish that something in the past had happened in a different way:

I should have studied for my exam!
(I didn’t study for my exams. I failed. Now I wish that the past was different.)

Should have can also be used to talk about something you expected to happen, but it didn’t happen (or it didn’t happen until later).

The letter should have arrived by now, but it hasn’t come yet.
(I was expecting a letter, but it isn’t here).

Now let's practice the adverbs of probability that we've learned at the beginning of this course!

You can use will and won’t with different adverbs to show how probable a future event is.

I’ll maybe go to the party.
I’ll probably go to the party.
I’ll definitely go to the party.
I’ll certainly go to the party.