7 M$ m4 s$ E/ B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: c6 C' i" t4 U4 v! s
Do they have to pay their bill before the end of the month?# @! y7 ^' w% [& A) _ k' D& P
She didn't use to play tennis before she was fourteen.0 T1 K. \% d9 l
You ought not to have told her all about it.
( S' P9 ?6 F1 O# p/ r4 s+ ] Ought he to see a heart specialist at once.?
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- F9 H2 M) Y7 `4 \! ~! s; e 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。
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典型例题
! ~- R/ R) U# b0 G3 T% V Tom ought not to ___ me your secret, but he meant no harm.
+ a. j6 S; m$ S' u( C w- r" h A.have told B.tell C.be telling D. having told; U# a, x/ b* X1 O# t
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。 |