Después de aprender Uses of Like, en esta lección aprenderemos Modal Verbs of Probability.

Podemos usar estos Modal Verbs of Probability (también llamados modales de deducción, especulación o certeza) cuando queremos adivinar algo.

Elegimos el verbo dependiendo de qué tan seguros estemos.

1: Talking about the present:

must / might / could / may / can’t + infinitive

For example:

I am waiting for Julie with another friend, David.
I ask: ‘Where is Julie?’
David guesses:

She must be on the bus. (I’m fairly sure this is a good guess)
She might come soon. (maybe)
She could be lost. (maybe)
She may be in the wrong room. (maybe)
She can’t be at home. (I’m fairly sure this isn’t true)

Notice that the opposite of ‘must‘ is ‘can’t in this case

Will / won’t

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

She’ll be at work now

Should / Shouldn’t

Should and shouldn’t are used to make an assumption about what is probably true, if everything is as we expect:

They should be 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:

The underground will be very busy now (not: ‘should be’)

Can

Can is used for something that is generally possible, something we know sometimes happens:

Prices can be high in London.

Can is not used to talk about specific possibilities:

He could be on the bus (not: ‘can be’)

2: Using modal verbs to talk about the past:

must / might / could / may / can’t + have + past participle

must have + past participle
might / might not have + past participle
could / couldn’t have + past participle
may / may not have + past participle
can’t have + past participle

For example:

You: Where was Janet last night?
David:

She must have forgotten about our date.
She might have worked late.
She could have taken the wrong bus.
She may have felt ill.
She can’t have stayed at home.

Will / won’t + have + past participle

Will and won’t / will not + have + past participle are used for past certainty (compare with present use of ‘will’ above):

The parcel will have arrived before now

Should + have + past participle

Should + have + past participle can be used to make an assumption about something that has probably happened, if everything is as we expect (compare with present use of ‘should’ above):

The train should have left by now

Could

We can use could + infinitive to talk about a general possibility in the past (compare with the use of ‘can’ above):

Prices could be high in the sixteenth century.

This is not used to talk about specific possibilites in the past (instead we use could + have + past participle):

He could have been working late (not: ‘could be’. As this is a specific possiblity, ‘could be’ is present tense)

En la próxima lección aprendermos Past Perfect.

Modal Verbs of Probability