Modal auxiliaries Substitutes Past Future can, could cannot/can’t, could not/couldn’t to be able to was/were able to will be able to may, can may not/mustn’t, cannot/can’t to be allowed to was/were allowed to will be allowed to must needn’t to have to had to will have to needn’t to not have to didn’t have to won’t have to b) Meaning of modal verbs Modal verbs express functions such as ability, obligation, possibility and permission. Modal verbs expressing ability How to use them Surprisingly many people can’t swim. Mike couldn’t find his swimming trunks yesterday. Lisa has been able to swim since she was five. • Can (cannot/can’t) and could (couldn’t) express that someone (or something) is/was able or unable to do something. Modal verbs expressing obligation How to use them I’m sorry, but I really must leave now. Thanks, but you needn’t drive me home. It’s not far to walk. You’ve had too much to drink. You really shouldn’t be driving. I think you ought to be more careful. • Must expresses that something is necessary or should be done. • Needn’t expresses that something is not necessary. • Should and ought to can be used to give advice or to express criticism. Modal verbs expressing possibility How to use them A: Surely this can’t be Tracy’s mobile, can it? B: You may be right. But whose is it? Ask Sarah, she might know. A: I think Tracy must have left hers at home. • Can, could, may and might express that something is possible or seems to be possible. Must expresses that the speaker expects something to be certain or very probable. Modal verbs expressing permission How to use them A: May we take photos in the cathedral, Mrs Dent? B: I don’t think you’re allowed to. There’s a sign that says, “Visitors are not permitted to take photos.” So I’m afraid you can’t. And you certainly mustn’t take your ice-cream inside, Sam. • May is used to ask for permission politely. Mustn’t, can’t and may not (more formal) are used to refuse permission. c) Negation of must and need Whereas most modal verbs can be negated regularly, the modal verb must changes its meaning when negated. Must/Must not Need/Need not I must change that. Ich muss das ändern. I mustn’t change that. Ich darf das nicht ändern. I needn’t do that. Ich brauche das nicht zu tun. I don’t have to do that. Ich muss das nicht tun. The passive voice In passive sentences the focus is on the activity itself. The emphasis is on what is done, while the “doer”, i.e the agent, is either obvious, unimportant or unknown. The same rules about which tense to use apply in both the passive and the active voice. However, only the present tense and the past tense are used in the progressive form. G 5 175 Nur zu Prüfzwecken – Eigentum des Verlags öbv
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