We can use these modal verbs (also called modals of deduction, speculation or certainty) when we want to make a guess about something. We choose the verb depending on how sure we are.
1: Talking about the present:
must / might / could / may / can't + infinitive
- 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
Should / shouldn't
- They should be there by now.
- It shouldn't take long to drive here.
- The underground will be very busy now (not: 'should be').
Can
- Prices can be high in London.
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
- 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
- The parcel will have arrived before now.
Should + have + past participle
- The train should have left by now
Could
- Prices could be high in the sixteenth century.
- He could have been working late (not: 'could be'. As this is a specific possiblity, 'could be' is present tense)
I'm here to help you understand grammar and speak correct, fluent English.
Made with love in London
