1. Modal verbs

2. eg1471/jc/dec2008 Forms of Modals Modals do not take third person -s √ The nurse can give the injection. x The nurse cans give the injection. The infinitive is used after the modal verb. √ The planes must take off now. √ The wastage can be stopped. √ The technical glitch could have been avoided. x She should recycles that paper.

3. eg1471/jc/dec2008 Forms of Modals In negative sentences, not follows the modal even when be or have are present. The investigation may not end today. √ The survey should not have yielded such results. √ The lecturer could not be there at this hour. √ The lecturer could be not there at this hour. x Do not use the contracted forms of negatives in formal writing. Use cannot and not can’t .

4. eg1471/jc/dec2008 Uses of Modals To express: ability degrees of possibility advisability necessity

5. eg1471/jc/dec2008 Modals Expressing Ability ModalsMeaningExample CanExpress (a lack of) physical ability or skill The new employee can drive. The astronaut cannot go up the space shuttle today. CouldExpress a (lack of) past ability or skill In the 1800s, people could not communicate with each other across the globe via email. Could have + past participle Refers to a past situation in which the ability for something to happen existed, but it didn’t happen. The team could have won. (However, they didn’t.)

6. eg1471/jc/dec2008 Modals Expressing Degrees of Possibility cannot may/might not should must Unlikely highly likely To express impossibility or near impossibility, use cannot. To express low possibility, use may/may not; might/might not; or could/could not. To express moderate possibility, use should/should not. To express high possibility or probability, use must. To express certainty or human intentions, use will/ will not. In the past context, use would/ would not. See Raimes (2006) pp. 74-75 for examples

7. eg1471/jc/dec2008 Modals Expressing Degrees of Possibility She’s very intelligent and has been studying hard so she will pass the test. √ She’s very intelligent and has been studying hard. She should pass the test. √ She’s very intelligent and has been studying hard so she cannot pass the test. X

8. eg1471/jc/dec2008 Modals Expressing Advisability To express whether something is a good idea or not, use should or should not. To express an advisable action that did not occur in the past, use should have + past participle. To express a past action that was not advisable, use should not have + past participle.

9. eg1471/jc/dec2008 Modals Expressing Necessity To express necessity, use must or has/have to. I must do my homework. (Must is internal) You have to wear a seatbelt when you drive. (Have to is external) To express lack of necessity, use do/does/did + not + have to. I don’t have to do my homework. To express a past necessity, use had to, not must. I had to do my homework last night. Must not expresses a prohibition, not a lack of necessity.

10. eg1471/jc/dec2008 Phrasal Alternatives to Modal Auxiliaries MeaningModal AuxiliaryPhrasal Alternative certaintywillbe going to abilitycanbe able to advisabilityshouldhad better, ought to, need to necessitymusthave to, have got to, be supposed to past necessityhad to lack of necessitydo not have to repeated past eventwouldused to

11. eg1471/jc/dec2008 Modal Auxiliaries Ranked by Strength Modal verbLogical probability meaning Social interaction meaning Strength willcertaintyintentionstrong weak mustlogical necessityobligation wouldconditional certainty conditionality shouldprobabilityadvisability maypossibilitypermission, possibility canpossibilitypermission might/couldlow possibilityvery polite permission, possibility

12. Common Error eg1471/jc/dec2008 The opposite of must has two forms:

13. eg1471/jc/dec2008 Sources Lane, A. and Lange, E. (1999). Writing Clearly: An Editing Guide (2 nd ed.). Boston: Heinle and Heinle Publishers, 50-65 Raimes, A. (2006). Grammar Troublespots: A Guide for Student Writers (3 rd ed.). New York: Cambridge University Press, 73-80.