Obligation, Necessity, And Prohibition


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Obligation, Necessity, And Prohibition

  1. 1. OBLIGATION, NECESSITY, AND PROHIBITION MUST, HAVE TO, HAVE GOT TO <ul><li>AFFIRMATIVE USE  strong obligation </li></ul><ul><li>We can use “must”, “have to” and “have got to” to express obligation. </li></ul><ul><li>Broadly speaking, when “must” is used, the obligation comes from the speaker, (internal obligation): </li></ul><ul><li>I really must stop smoking. </li></ul>
  2. 2. OBLIGATION, NECESSITY, AND PROHIBITION MUST, HAVE TO, HAVE GOT TO <ul><li>If we talk about or report an obligation that comes from “outside” (for example: a regulation or order from somebody else) </li></ul><ul><ul><ul><li>“ must” is possible (especially in written rules)  </li></ul></ul></ul><ul><ul><ul><li>Cars must not be parked here. </li></ul></ul></ul><ul><ul><ul><li>“ have to” is more common  </li></ul></ul></ul><ul><ul><ul><li>I have to work from 9 a.m till 5 p.m. (an order from the boss) </li></ul></ul></ul><ul><ul><ul><li>“ have got to” is usually only used in spoken English or written fiction. It can be used for “external” and “internal” obligation  </li></ul></ul></ul><ul><ul><ul><li>I’ve got to post this letter before 7 0’clock. </li></ul></ul></ul>
  3. 3. OBLIGATION, NECESSITY, AND PROHIBITION MUST, HAVE TO, HAVE GOT TO <ul><li>NEGATIVE USE </li></ul><ul><ul><ul><li>In negative sentences “don’t need to”, “needn’t”, “don’t have to” or “haven’t got to” is used to say that there’s no obligation;  </li></ul></ul></ul><ul><ul><ul><ul><ul><li>you needn’t work tomorrow if you don’t want to. </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>(NOT  mustn’t) </li></ul></ul></ul></ul></ul><ul><ul><ul><li>“ Mustn’t” is used to tell people not to do things; means that something is wrong, dangerous or not permitted  </li></ul></ul></ul><ul><ul><ul><ul><ul><li>you mustn’t move any paper on my desk. </li></ul></ul></ul></ul></ul>
  4. 4. SHOULD AND OUGHT TO <ul><li>“ Should” and “ought to” are used to express mild obligation and duty, and in general to say what we think it is good for people to do  </li></ul><ul><ul><ul><li>you shouldn’t work too hard. </li></ul></ul></ul><ul><li>In most cases, both “should” and “ought to” can be used with more or less the same meaning. </li></ul><ul><ul><ul><li>You should /ought to go and see your uncle. He’s very ill. </li></ul></ul></ul>
  5. 5. SHOULD AND OUGHT TO <ul><li>However, there is a slight difference: </li></ul><ul><ul><li>When we use “should” we give our own subjective opinion; </li></ul></ul><ul><ul><li>“ Ought to” has a rather more objective force, and is used when we talk about laws, duties and regulations. </li></ul></ul><ul><ul><ul><ul><li>We ought to go and see your uncle next week, but I don’t think we will. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>It would sound strange to use should and then add we are not going to see him. </li></ul></ul></ul></ul>
  6. 6. BE ALLOWED TO + infinitive <ul><li>It’s used to talk about things you can do or are permitted to do. </li></ul><ul><li>It is similar in meaning with “permit”, however “permit” is a little more formal. </li></ul><ul><li>Both verbs can be followed by OBJECT + INFINITIVE </li></ul><ul><ul><ul><li>We don’t allow people to smoke in class. </li></ul></ul></ul><ul><li>It’s worth stating here that when there is no personal object , a gerund (-ing form) is used  </li></ul><ul><ul><ul><li>We don’t allow smoking in class. </li></ul></ul></ul>
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