情态动词+to 比如这句 The doctor did what he could to save her baby.为什么要加to?

情态动词+to 比如这句 The doctor did what he could to save her baby.为什么要加to? used to算不算情态动词?参考书上说 情态动词不能表示正在发生或已经发生的事情,只表示期待或估计某事的发生.可是I used to get up early in the past.这句也是情态动词的句子,却是表示过去的,这句 情态动词後不加to? 如果句子中有情态动词,比如may,must,can时,要求写该句的反意疑问句?比如，He may carry the apples here----------？ dare做情态动词时可以加ed吗?比如,I dared not open the window==I didn't dare (to) open the window 】 什情态动词后要加to 特殊疑问句 比如 why do you love me?里面可以加情态动词吗,比如为什么车能跑 why do the cars can run.这里面能加情态动词吗, have to是实义动词还是情态动词 情态动词+动词不定式表示什么The girl does everything she can to become famous. would ought to 作为情态动词通常用在肯定句疑问句还是否定句? 情态动词是实词吗,比如Could you pass me the salt中的Could? 这句话中有情态动词吗?求指出!Jack WAS SEEN TO SWIM across the river. 怎么区分这句话是用实义动词还是用情态动词eg:how does he walk to work?how can he get to the post office? We also have to be quiet in the library这个是书上的原句 不是说also出现在情态动词的后面么? 关于一个情态动词的意思Why should I have to do all the washing up!在这里我看到了情态动词should,又有have to 这中什么用法怎么理解 分析这句英文的语法A planet would have to be a very long way from it to be capable of supporting life.1、would是情态动词have to 也相当于情态动词,不是两个情态动词不能连用吗?2、句子中前后两和be又是什么用 填写情态动词The teacher is free now.You()talk to him.填写情态动词The teacher is free now.You()talk to him. would you like to go to the movies?中的would 是情态动词么?