专四语法专题第七节:情态助动词I.情态助动词考点与知识要点:———————————————————————————————————————情态助动词概述:情态助动词有 can (could), may (might), must, have to, shall (should, will (would), dare (dared), need (needed), ought to 等。 情态动词无人称与数得变化;不能单独使用,必须与其后得动词原形构成谓语。———————————————————————————————————————情态助动词知识要点:1. can / could2. may / might3. will, would4. shall5. should, ought to6. must7. need8. dare9. 情态动词+不定式完成式(have done)1.can / could1) 表示请求与允许(Permission) -----Can I go now? ----- Yes, you can、 / No, you can’t、 此时可与 may 互换。在疑问句中还可用 could,might 代替,不就是过去式,只就是语气更委婉,不能用于肯定句与答语中。 ---- Could I e to see you tomorrow? ---- Yes, you can、 ( No, I’m afraid not、 )2) 表示能力(体力、知识、技能)(Ability)Can you lift this heavy box?(体力)Mary can speak three languages、(知识)Can you skate?(技能)表示“能力”时可与 be able to 互换。Can 只有一般现在时与一般过去式;而 be able to 则有更多得时态。I’ll not be able to e this afternoon、但当表示“经过努力才得以做成功某事”时应用 be able to,不能用 Can。如:He was able to go to the party yesterday evening in spite of the heavy rain、3) 表示客观可能性(客观原因形成得能力)(Possibility) They’ve changed the timetable, so we can go by bus instead、 This hall can hold 500 people at least、4) 表示推测(惊讶、怀疑、不信任得态度),用于疑问句、否定句与感叹句中。 Can this be true? This can’t be done by him、 How can this be true?2.may / might 1) 表示请求与允许(Permission)。might 比 may 语气更委婉,而不就是过去式。否定回答时可用 can’t 或 mustn’t,表示“不可以,禁止”。 ----Might/ May I smoke in this room? ---- No, you mustn’t、 ---- May/Might I take this book out of the room?...
