关于带to 的情态动词

maizai

" ~( v# O+ h, b2 l3 C) l6 u' `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? 9 d8 X g, a$ w　 She didn't use to play tennis before she was fourteen. . M4 J2 L2 [ h2 p) e4 H　 You ought not to have told her all about it. A# M9 L; T! Q$ `* W3 b" K　 Ought he to see a heart specialist at once.? ) n, E& a; E' n3 e! ~* E # l+ V/ ~; h3 z- ?3 x- c, d　 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 told　B.tell　C.be telling　D. 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。