情态动词(Modal verbs)本身有一定的词义,表示语气的单词。但是不能独立作谓语,只能和动词原形一起构成谓语。情态动词用在行为动词前,表示说话人对这一动作或状态的看法或主观设想。 情态动词虽然数量不多,但用途广泛,主要有下列: can (could), may (might), must, need, ought to, dare (dared), shall (should), will (would) must
①只做情态动词:may, might, must…
②可做情态动词又可做实义动词:如:need, dare…
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)
⒈ 在表示愿望的动词wish后的宾语从句中,需用虚拟语气.(wish后的that 常省略),根据主句时态,从句谓语时态相应退后一位,例如:How she wished his family could go with him.
⒉ 在具有愿望、请求、建议、命令等主观意愿的动词(desire, demand, advice, insist, require, suggest, propose, order, recommend, decide …) 后的宾语从句中需用虚拟语气.谓语动词用(should) +动词原形.值得注意的是,如果宾语从句的动词是否定的,否定词not的位置应在动词之前,而不是动词之后.例如:The head nurse insisted that the patient not be move.另外,如suggest表达“暗示”,insist表示“坚持某种说法”时,后面的从句不用虚拟语气,例如:Her pale face suggests that she is ill.或He insisted that he did not kill the boy.
以上就是一些情态动词的相关信息,希望对大家有所帮助。