Probability
Probability chapter contains Possibility Impossibility and Certainty subsections
Possibility
We use may, might and could to say that something is possible, but not certain:
They may come by car. (= Maybe they will come by car.)
They might be at home. (= Maybe they are at home.)
If we don't hurry, we could be late. (= Maybe we will be late.)
We use can to make general statements about what is possible:
It can be very cold here in winter. (= It is sometimes very cold here in winter.)
Notice the difference in meaning between can and may/might/could:
That dog can be dangerous.
(= Sometimes that dog is dangerous. I know.)
That dog might be dangerous.
(= May be that dog is dangerous. I don't know.)
Impossibility
We use can't or cannot to say that something is impossible:
That can't be true.
You cannot be serious.
Certainty
We use must to show we are sure something is true and we have reasons for our conclusion:
It's getting dark. It must be quite late. / Темнеет. Должно быть (это значит), уже довольно поздно.
You haven’t eaten all day. You must be hungry. /Вы не ели весь день. Должно быть (значит) вы голодны..
We use should to suggest something is true and we have reasons for our suggestion:
Ask Miranda. She should know. / Спросите Миранду. По идее, она должна знать.
It's nearly six o'clock. They should arrive soon. / Уже почти шесть. Они должны прибыть в ближайшее время.
