Simone
四大分类①只做情态动词:must,may…… ②可做情态动词又可做实义动词：如：need, dare,can....... ③具有情态动词特征：have(had,has) to,used to, ought to ④可做情态动词又可作助动词：如：shall(should),will(would)[1] 注意mustn't代表强烈禁止轮巧 must表示主观，have to表示客观。斗桐带 美式空芦英语中常用must not 而不用 mustn't. mayn't,mightn't和shan't也很少用常用can (could), may (might), must, need, ought to, dare (dared), shall (should), will (would)
