今天小编为大家分享的是
英语四级语法知识之带to 的情态动词,带to 的情态动词有四个,想知道那四个吗?快来跟随小编学习下吧,希望通过这篇文章的学习对你们有所帮助,下面跟随小编一起学习吧。
带to 的情态动词
带to 的情态动词有四个:ought to, have to, used to, be to, 如加上have got to ,(=must), be able to,为六个。它们的疑问,否定形式应予以注意:
Do they have to pay their bill before the end of the month?
She didn't use to play tennis before she was fourteen. You ought not to have told her all about it.
Ought he to see a heart specialist at once.?
ought to 本身作为情态动词使用。其他的词作为实义动词使用,变疑问,否定时,须有do 等助动词协助。

典型例题
Tom ought not to ___ me your secret, but he meant no harm.
A.have toldB.tellC.be tellingD. having told
答案A。由于后句为过去时,告诉秘密的动作又发生在其前因,此地应用过去完成时,但它在情态动词 ought to 后,所以用have。