1.dare, need① dare作情态动词用时, 常用于疑问句、否定句和条件从句中, 过去式形式为dared。 例How dare you say such horrible words to me? ② need 作情态动词用时, 常用于疑问句、否定句,相当于肯定句中一般用must, have to, ought to, should。 例 Need I finish the work today? Yes, you must. / No, you needn’t. ③ dare和 need作实义动词用时,有人称、时态和数的变化,在肯定句中,dare后面常接带to的不定式,在疑问句和否定句中,dare后面可接带to或不带to的不定式,而need后面只能接带to的不定式。 例 She doesn’t dare (to)answer. 2.shall, should① shall 用于第一人称,征求对方的意见。 例:What shall I do ? ② shall 用于第二、三人称,表示说话人给对方的命令、警告、允诺或威胁。 例:You shall be punished,you bad boy! 3.will, would①表示请求、建议等,使用would使语气更加缓和。 例Would you give me a cup of coffee, please? ②表示意志、愿望和决心。 例 I will never do that again. ③ would表示过去反复发生的动作或某种倾向。 例During that summer, he would visit me everyother day. ④表示估计和猜想。 例It would be about may when she come back toChina. 4.should, ought to① should表示“应该”,ought to表示义务或责任,语气更严重。 例 I should help her because she is introuble. ②表示劝告、建议和命令,should, ought to可通用,但在疑问句中常用should。 例 Should I open the window? ③表示推测, should , ought to (客观推测), must(主观推测)。 例She must pass the exam. (断定) |
|