Modals for speculation

 

When speculating in English use modals of deduction.

• 1. If you are speculating about something in the present or present actions use: must / may / might / could / can’t + be

 

Must be - when you are almost certain something is true, based on the

evidence.

 

Might/may/could be - when you think it is possible that something could be true.

 

Can’t be - when you are almost certain something is not true or impossible.

It’s already 3 o’clock. They should be here by now. They must be about to arrive, because they called me to say they’d be here in 10 minutes. They can’t be lost because they’ve been to my house before and they know how to get here. Well, they might be caught in traffic because rush hour starts about now.

• 2. If you are speculating about something in the past or past actions use past modals: must / may / might / could / can’t + have + past participle.

 

Must have been - when you are almost certain something is true, based on the evidence

 

Might/may/could have been - when you think it is possible that something could be true

 

Can’t have been - when you are almost certain something is not true or impossible.

Now, imagine that her friends have arrived and explain why they were late.   Friend 1: Hi there. I can’t believe we’ve finally made it! Sorry we’re late but there was a huge traffic jam and we were caught up in it for over an hour. Friend 2: It must have been some kind of accident, you know, an overturned truck or something like that. Friend 1: Yeah, but it can’t have been an accident or we would have seen some ambulances or something. Friend 2: Well, there might not have been any injuries and that’s why there were no ambulances, just a lot of police cars. Friend 1: Anyway, we’re sorry we should have rung* you. We just didn’t think.

* You can use should have/ought to have + past participle to say that you/someone didn’t do the right thing.