Forms of Modals • Modals do not take on -s as they do not indicate number or person. The nurse can give the injection. The computerswill process the information. • The base form of the verb is used after the modal verb. The planes musttakeoff now. The wastage canbestopped. The technical glitch could havebeen avoided.
Forms of Modals • When modals take on the negative not, the latter follows the modal even when be or have are present. The investigation may not end today. The survey should not have yielded such skewed results. The gamers could not be there at this hour. Do not use the contracted forms of negative modals in formal writing. Use cannotand notcan not .
Uses of Modals • To express ability • To express degrees of possibility • To express advisability • To express necessity or lack of necessity
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
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.
Modals Expressing Necessity or Lack of Necessity • To express necessity, use must or the phrasal verbs has/have to. • To express lack of necessity, use the phrasal alternative do/does/did have to. • To express a necessity in the past, use had to. Must not expresses a prohibition, not a lack of necessity.
Sources Lane, A. and Lange, E. (1999). Writing Clearly: An Editing Guide (2nd ed.). Boston: Heinle and Heinle Publishers, 50-65 Raimes, A. (2006). Grammar Troublespots: A Guide for Student Writers (3rd ed.). New York: Cambridge University Press, 73-80.