Modals Probability and Certainty Modals Probability and Certainty
Modals - Probability and Certainty
Modals - Probability and Certainty • The following modal verbs can be used to express probability or certainty: – You use ‘must’, ‘ought’, ‘should’, or ‘will’ to express probability or certainty. – You use ‘cannot’ or ‘can’t’ as the negative of ‘must’ rather than ‘must not’ or ‘mustn’t’, to say that something is probable or not certain.
Modals - Probability and Certainty • When you want to say that something is probably true or that it will probably happen, you use ‘should’ or ‘ought’. ‘Should’ is followed by the base form of a verb. ‘Ought’ is followed by a ‘to’infinitive. – We should arrive by dinner time. – She ought to know.
Modals - Probability and Certainty • When you want to say that you think something is probably not true or that it will probably not happen, you use ‘should not’, or ‘ought not’. – There shouldn’t be any problem. – That ought not be too difficult.
Modals - Probability and Certainty • When you want to say that you are fairly sure that something has happened, you use ‘should have’ or ‘ought to have’, followed by a past participle. – You should have heard by now that I’m O. K. – They ought to have arrived yesterday.
Modals - Probability and Certainty • When you want to say that you do not think that something has happened, you use ‘should not have’ or ‘ought not to have’, followed by a past participle. – You shouldn’t have had any difficulty in getting there. – This ought not to have been a problem.
Modals - Probability and Certainty • You also use ‘should have’ or ‘ought to have’ to say that you expected something to happen, but that it did not happen. – Yesterday should have been the start of the soccer season. – She ought to have been home by now. Note: You do not normally use the negative form with this meaning.
Modals - Probability and Certainty • When you are fairly sure that something is the case, you use ‘must’. – Oh, you must be Sylvia’s husband. – You must know something about it.
Modals - Probability and Certainty • If you are very sure something is not the case, you use ‘cannot’ or ‘can’t’. – This cannot be the whole story. – He can’t be very old -- he’s about 25, isn’t he? Note: You do not use ‘must not’ or ‘mustn’t’ with this meaning.
Modals - Probability and Certainty • When you want to say that you are almost certain that something has happened, you use ‘must have’, followed by a past participle. – This article must have been written by a woman. – We must have taken the wrong road.
Modals - Probability and Certainty • To say that you do not think something has happened, you use ‘can’t have’, followed by a past participle. – You can’t have forgotten me. – He can’t have said that.
Modals - Probability and Certainty • You use ‘will’, or ‘-’ll’ to say that something is certain to happen in the future. – People will always say thing you want to hear. – They’ll manage.
Modals - Probability and Certainty • You use ‘will not’, or ‘won’t’ to say that something is certain not to happen. – You won’t get much sympathy from them.
Modals - Probability and Certainty • There are several ways of talking about probability or certainty without using modals. For example, you can use: – ‘bound to’ followed by the base form of a verb. • It is bound to happen. • You’re bound to make a mistake.
Modals - Probability and Certainty – An adjective such as ‘certain’, ‘likely’, ‘sure’, or ‘unlikely’, followed by a ‘to’-infinitive clause or a ‘that’-clause. • They were certain that you were defeated. • I’m not likely to forget it.
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