Should must have to


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Should must have to

  1. 1. Should vs. Must Stores must give out recyclable plastic bags. We should use re-usable bags when shopping. The car industry must change engines that burn fossil fuels. We should select cars that are more fuel-efficient. We must protect our environment, or our resources will disappear. We should protect our environment. It makes good sense. We use must to express a stronger point of view. "We need to..." "We have to..." The modal must also expresses opinion, one person's point of view. We use should to suggest something. "It is advisable to..." The modal should expresses opinion, one person's point of view. MUST SHOULD
  2. 2. Must (subjective obligation) We often use must to say that something is essential or necessary (strong advice), for example: I must go. You must stay here Structure of Must Must is a modal auxiliary verb. It is followed by a main verb. The structure is: subject + must + main verb The main verb is the base verb (infinitive without "to"). Look at these examples:
  3. 3. <ul><li>Like all auxiliary verbs, must CANNOT be followed by to . So, we say: </li></ul><ul><li>I must go now. ( not * I must to go now .) </li></ul>now. stop must We us. visit must You home. go must I main verb auxiliary must subject
  4. 4. In general, must expresses personal obligation. Must expresses what the speaker thinks is necessary. Must is subjective . Look at these examples : I must stop smoking. You must visit us soon. He must work harder . In each of the above cases, the &quot;obligation&quot; is the opinion or idea of the person speaking. In fact, it is not a real obligation. It is not imposed from outside .
  5. 5. <ul><li>It is sometimes possible to use must </li></ul><ul><li>for real obligation, for example a rule or a law. </li></ul><ul><li>But generally we use have to for this. </li></ul><ul><li>We can use must to talk about the present or the future . </li></ul><ul><li>Look at these examples: </li></ul><ul><li>I must go now. ( present) </li></ul><ul><li>I must call my mother tomorrow. ( future) </li></ul><ul><li>*** We cannot use must to talk about the past . </li></ul><ul><li>WE use had to. </li></ul>
  6. 6. MUST NOT (mustn’t ) <ul><li>Must not expresses prohibition - something that is not permitted, not allowed . </li></ul><ul><li>I mustn't eat so much sugar. </li></ul><ul><li>You mustn't watch so much television. </li></ul><ul><li>Students must not leave bicycles here. </li></ul><ul><li>Policemen must not drink on duty. </li></ul>
  7. 7. HAVE TO <ul><li>We often use have to to say that something is obligatory, for example: </li></ul><ul><li>Children have to go to school. </li></ul><ul><li>Structure of Have to </li></ul><ul><li>Have to is often grouped with modal auxiliary verbs for convenience, but in fact it is not a modal verb. It is not even an auxiliary verb. </li></ul><ul><li>In the have to structure, &quot;have&quot; is a main verb . The structure is: </li></ul><ul><li>subject + auxiliary verb + have + infinitive (with to ) </li></ul>
  8. 8. <ul><li>Look at these examples in the simple tense : </li></ul>to school? to go have you Did ? the doctor. to see have do not ( don’t ) Does not( doesn’t ) I She - all day. to work. has She + infinitive (with to ) main verb have auxiliary verb subject
  9. 9. Use of Have to <ul><li>In general, have to expresses impersonal obligation . The subject of have to is obliged or forced to act by a separate, external power (for example, the Law or school rules). </li></ul><ul><li>Have to is objective . Look at these examples: </li></ul><ul><li>In France, you have to drive on the right. </li></ul><ul><li>In England, most schoolchildren have to wear a uniform. </li></ul><ul><li>John has to wear a tie at work . </li></ul><ul><li>In each of the above cases, the obligation is not the subject's opinion or idea. The obligation is imposed from outside. </li></ul>
  10. 10. We can use have to in all tenses , and also with modal auxiliaries. We conjugate it just like any other main verb. Here are some examples: it again. to do have may They modal (may) the time. to change had have We present perfect to wait. having is She present continuous tomorrow. to work have will I future simple today. to work have I present simple yesterday. to work had I past simple infinitive main verb have auxiliary verb subject
  11. 11. DOES/DO NOT have to <ul><li>Have to in the negative form means it’s NOT NECESSARY. </li></ul><ul><li>Tomorrow is Sunday, I don’t have to go to work. </li></ul><ul><li>She doesn’t have to pay , it’s free. </li></ul><ul><li>You don’t have to wait for me, I can take the bus… (but if you want to wait, it’s OK.) </li></ul>
  12. 12. Angela, you ______leave your clothes all over the floor like this. 10 Bicyclists ______remember to signal when they turn. 9 Do you ________work next weekend? 8 You _______come if you don’t want to. 7 Your daughter may _____ try on a few different sizes. 6 If you are under 13 you ____ get your parents' permission. 5 We ______forget to take the chicken out of the freezer. 4 All employees ________be on time for work. 3 She will _____wait in line like everyone else. 2 Yesterday I_______ finish my Geography project.
  13. 13. ANSWERS <ul><li>1. had to </li></ul><ul><li>2. have to </li></ul><ul><li>3. have to </li></ul><ul><li>4. mustn’t </li></ul><ul><li>5 have to/must </li></ul><ul><li>6. have </li></ul><ul><li>7. don’t have to </li></ul><ul><li>8. have to </li></ul><ul><li>9. must </li></ul><ul><li>10. mustn’t </li></ul>