1、四、语法详解1.ought to(1)表义务,意为“应该” (在责任、义务上等该做) ,口气比 should 稍重。You are his father.You ought to take care of him.你是他父亲,应当管他。You ought not to smoke so much.你不应该抽这么多烟。(2)含有 ought to 的反意疑问句,陈述部分是肯定的,疑问部分用 shouldnt/oughtnt +主语。He ought to know what to do, oughtnt he?/shouldnt he?活学巧用1.1)单项选择There is a lot of
2、smoke coming out of the teaching-building there.Really?It _ be a fire,most probably.A.can B.ought to C.have to D.must答案:B2)完成句子Zhou Lan ought to pass the National College Entrance Examinations,_she?答案:oughtnt/shouldnt2.have to 通常指由于客观原因而不得不做某事,意思为 “不得不” 。Its dark now.I have to go home.天黑了,我不得不回家了。It
3、s raining,and I have to stay at home.外面在下雨,我不得不待在家里。have to 与一般情态动词的不同点:(1)一般的情态动词没有人称和数的变化,而且所用的时态也受到一定的限制,而 have to 有人称和数的变化,可用于多种时态中:一般现在时中,当主语是第三人称单数时要用has to,其余的人称用 have to;一般过去时中要用 had to;一般将来时中则要用 will have to。(2)否定句和疑问句的构成方式不同:一般的情态动词直接在后面加 not 构成否定句,把这些情态动词提到句首就构成一般疑问句。而 have to 的否定句和疑问句的构成
4、需要借助于助动词 do 的适当形式或助动词 will 即have to,has to,had to 和 will have to 的否定式分别为 dont have to,doesnt have to,didnt have to 和 wont have to,疑问句是在句首加助动词 do 的相应形式,句中还原成 have to 或把 will放到句首。活学巧用2.1)单项选择(1)Well _ finish the job,however long it takes.A.ought to B.mustC.have to D.should答案:C(2)Do you know the diffic
5、ulty he had _ the work?A.on finishing B.to finishC.finishing D.having finished提示:题中 he hadthe work 是定语从句,修饰 difficulty。 have difficulty(in) doing sth.是固定句型。关系代词 that 被省略,in 也被省略,故出现 had 与 finishing 相邻的情况。此题易误选 B。答案:C2)完成句子I _ _ _ _my notebooks for the exam.为了考试我必须把笔记复习一遍。答案:have to look through3.nee
6、d 表示“需要” ,主要用于否定句和疑问句用于疑问句,肯定回答用 must,否定回答用 neednt。have to 表示他人或客观情况要求“必须” ,也可以翻译为“不得不” ,have to 否定形式意思是“不一定”或“没有必要” 。4.must“必须做某事” ;mustnt 用来警告别人“一定不要做某事 ”We must obey the rules.我们必须遵守规则。We must respect old people and help them.我们必须尊重老人,并且帮助他们。You mustnt play in the street.你一定不能在街道上玩耍。活学巧用3.翻译句子(1)你必须照顾好你妈妈。You _ take good care of your mother.答案:must(2)严禁在此处游泳。You _ _ here.答案:mustnt swim(3)请勿践踏草坪。You _ _ off the grass.答案:must keep