2 Modals and semi-modals Can, may, must…They are the same for all persons.You must pay attention.They don’t need an auxiliary verb for questions and negatives:You shouldn’t swim when it’s windy.Should I stay with you?Two modal verbs can’t be used in the same phrase:I will can play again next month (*).Be able to, have toThey aren’t the same for all persons.You have to pay attention / She has to pay attention.They may need an auxiliary for questions and negatives:You don’t have to say you’re sorry.Do we have to speak in English?They’re used when the modals can’t be used.I will be able to play again next month.
3 SIMPLE MODALS Must / have to Obligation I must go to the hospital Logical deduction (only must)The film must be very good. Everybody likes it.Can’tLogical deductionThis person can’t be Michael. He’s too short.Don’t have toLack of obligationYou don’t have to say you love me.Mustn’t / can’tProhibitionWe mustn’t smoke at school.We can’t skip classes.Can (past, could) / be able toAbilityShe can swim very fast.I couldn’t concentrate yesterday.Next year, I will be able to speak three languages.Should / ought toAdviceYou should listen to your teachers.May / mightPossibilityIt may rain this afternoon. It’s very cloudy.Can / could / maypermissionCan I come in, please?ShallOffering (used only in questions and with 1st persons)Shall we continue?Shall I give you my phone number?
4 PERFECT MODALS PERFECT MODALS: MODAL + HAVE + PAST PARTICIPLE Should haveCriticism about a past actionYou should have made a bigger effort.You shouldn’t have used the present simple so often.Must haveLogical deduction about something in the pastIt must have been love, but it’s over now.You must have worked very hard. I can see you’re so tired!Could haveAbility to have done something which wasn’t done.You could have written some more.Couldn’t haveDisbeliefYou couldn’t have finished so quickly. It’s impossible!Needn’t haveAn unnecessary past actionYou needn’t have brought that bottle of wine. We have got plenty of it here.Might / may haveGuessing about a possibility in the pastShe might have forgotten to do her homework.Would havePast conditional: you wanted to do something, but you couldn’tI would have gone to her party, but I wasn’t invited.