- Must + inf: We use must + inf to say that we are almost sure something is true about the present.
She must be really happy. She has passed her exam.
- Must have + past participle : to say that we are almost sure something was true in the past.
My shoes aren't in their place. Someone must have moved them.
- Can't + inf: to say we are almost sure that something isn't true in the present.
They can't be playing very well, they are losing the game.
- Can't have + past participle: to say that we are almost sure that something didn't happen in the past. We don't use musn't / musn't have for this meaning.
I can't have lost my keys, I just saw them in my bag.
- May / might / could + inf may have /might have could have + past participle : to say that we think it's possible that something is true in the present or was true in the past. We only use may not or might not to talk about a negative possibility not couldn't.
Paul might have got lost. He has no sense of direction.
- Should / ought to + inf: to describe a situation we expect to happen.
If I post the letter today, it should /ought to arrive tomorrow.
- Should have / ought to have + past participle: to describe a situation we would expect to have happened in the past.
I posted the letter a week ago, it should / ought to have arrived on Monday.
- Be bound / sure + inf: bound and sure are adjectives. We use be bound / be sure to + inf to say we think something is certain to be true.
He's bound /sure to be late. Today there is a lot of traffic.
- Likely and unlikely: Both are adjectives not adverbs. We can use subject + be likely / unlikely to + inf, or it's likely / unlikely that + clause
I think she's likely to agree to our proposal
It is likely that the government will increase fuel taxes.
- Definitely and probably: Both are adverbs, they go before a main verb and after the auxiliary in positive sentences and before the auxiliary in negative sentences. With the verb to be they go after the verb in positive sentences and before the verb in negative sentences.
He will definitely pass the exam. He has prepared it thoroughly.
He definitely won't pass the exam. He has not had enough time to prepare it.