3) 表示惊异、怀疑、不相信的态度。(主要用在否定句、疑问句或惊叹句中)

Can this be true? ______________________

How can you be so careless! ___________________

This cannot be done by him. __________________

4)在变否定句时，直接在后加上“not”,可缩写成_________或___________, 但不能写成cann’t。例如：

(变成否定句) He can swim. → _______________________

3 ought意思是______________后面跟带有 to 的动词不定式否定式为_________________。(C级)

You ought to read these books if you want to know how to repair the motorcar.

____________________________________________

You ought to bring the child here.

_____________________________________________

You ought not to walk alone at night. _____________________________________________

注意： ought to和should的区别：

1.ought to语气略强。 2.should较常用。

3.ought to在美国英语中用的很少，而should却相当常用。

4.ought to属正式用语。

练一练：(C级)

1The man in the office____________be Mr. Black because he went home

just now.

A. mustn’t B. may not C. can’t D. needn’t

2---Can you go surfing with us this afternoon?

----I’d like to , but I ________ look after my sister at home , because my mother is ill.

A. need B. must C. have to D. should

3----Can I take this book out of the reading room?