This document discusses different ways to express obligation, necessity, prohibition, and advice in English using modal verbs and expressions. It explains that "must" and "have to" both express obligation or necessity, with "have to" being more common for general rules and "must" for specific instances. "Don't have to" means there is no obligation, while "mustn't" expresses prohibition. "Should" and "shouldn't" are used to give advice or opinion, with "should" being less strong than "must" or "have to". The document provides examples for how to use each expression appropriately.

1. Must, haveto, shouldOBLIGATIONNEFi 3A

2. OverviewObligation/necessity: haveto / must+ infinitiveNo obligation /necessity: don’thaveto+ infinitiveProhibition: mustn’t + infinitiveAdviceoropinion: should/shouldn’t+ infinitive

3. Obligation/Necessityhavetoormust+ infinitiveMust and havetohave a similar meaningHavetois more commonforgeneral, externalobligations (like rules orlaws)I havetowear a shirt and tie at work(it’s a rule)Mustis more commonforspecific (i.e.ononeoccasion) orpersonalobligationsI mustbuy a new shirt – thisoneistoooldnowYou can use havetoormustforstrongrecommendationsYouhaveto/ mustseethat film. It’sfantastic.

4. Obligation/Necessityhavetoormust+ infinitiveHavetois a normal verb and itexists in all tensesMustis a modal verb. The onlyforms are must and mustn’t. Forallother tenses, use haveto.Havegottoisoftenusedinstead of havetoin spokenEnglishI’vegottogonow. it’svery late.

5. No obligation /necessity: don’thaveto+ infinitiveProhibition: mustn’t + infinitiveUse don’thavetotosaythatyou can do something, butit’snotnecessary/you’renotobligedto do it.You can also use needn’t + infinitivewiththesamemeaningDon’thavetoand mustn’t are completelydifferent in meaning. Compare: Youmustn’t drive alongthisstreet(it’sagainstthelaw, prohibited)Youdon’thavetodrive – we can get a train(= you can drive ifyouwant, butit’snotnecessary/obligatory)

6. Prohibition: mustn’t + infinitiveYou can often use can’tornotallowedtoinstead of mustn’tYoumustn’tparkhereYoucan’tparkhereYou’renotallowedtoparkhere

7. Adviceoropinion: should/shouldn’t+ infinitiveShouldisnot as strong as must / haveto. We use ittosayifwethinksomethingistherightorwrongthingto do.Youshouldtakewarmclothes, as itmightbecold at night.The governmentshould do somethingabouttheproblem.

8. Adviceoropinion: should/shouldn’t+ infinitiveShouldis a modal verb. The onlyforms are should and shouldn’tYou can also use oughttooroughtnottowiththesamemeaningYoushouldtakewarmclotheswithyoutoDublin.YououghttotakewarmclotheswithyoutoDublin.