专题六
情态动词
1.Shall 1)用于第一,三人称的疑问句中,表示征求对方的意见,如:
What shall I wear on the journey? 我路上穿什么好呢? Shall we dance? 我们跳舞好吗? 2)shall 用于第二、三人称时表允诺,警告,命令,威胁,如:
She shall get her share. 她能够得到她的一份。
You shall have it back tomorrow.你明天能够将它拿回。
2.must 1)表示禁止(用于否定句)如:
Smoking must not be allowed in the office.严禁在办公室抽烟。
2)表示偏执、固执,常译成“一定要,非要”。如:
Why must you be talking so loudly while others are studying?为什么在别人学习的时候,你非要这么大声说话呢? 3.Should 1)表示根据经验常识预测可能性,并意为“(按道理)应该”如:
It is nearly 7oclock.Jack should be here at the moment.快 7 点了,杰克此刻应该在这儿了。
2)竟然,居然。如:
I am surprised that you should speak in such a way.我很惊奇你居然用那种语气说话。
4.would 和 used to
would 课表示过去反复发生的动作或某种倾向,后面接表示动作的动词,不能接表示状态的词。used to 表示过去的习惯动作或状态,强调现在已不存有。如:
He would come to see us on Sundays.过去他经常星期天来看望我们。
Our company used to do business with theirs.过去我们公司和他们公司常有业务往来。
5.can 和 could 的用法 1)表示惊讶,常用在否定句和疑问句中。如:
How could you do such a silly thing?你怎么能做那样的蠢事呢? 2)cannot...too/enough 表示“无论也不过度”,“越...越好”。如:
You cannot be too careful while driving .开车时越小心越好。
6.“may as well+动词原形”意为“最好,不妨,倒不如”。如:
You may as well do it at once.你最好马上就做那件事。
We may as well stay where we are.我们留在现在的地方倒也不错。
考点二 :
情态动词表“推测”
句型时 态 肯 定 推 测 否 定 推 测 疑 问 推 测
对现在的推测 Must/can/may+be Can’t+be Can sb be---?
对过去的推测 Must/can/may / might could+have done can’t/couldn’t/may not/ might not+have done Can/could sb+have done?
对将来的推测 Must/can/may/could Might+do Can’t/may not+do Can/may/+do? 对现在或将来发 生事情的推测 Must/may/can+be doing Can’t be doing Can sb be doing?
对过去正在发生
事情的推测 Must+have been doing Can’t+have been doing Can sb have been
doing? (一)情态动词表推测的三种句型 1.在肯定句中一般用 must (一定),may(可能),might / could(也许,或许)。
如:
(1)He must/may/might know the answer to this question? 他一定/可能/也许知道这个问题的答案。
(2)It is cold in the room. They must have turned off the heating. 屋里很冷,他们肯定把暖气
关了。
2.否定句中用 can’t / couldn’t(不可能), may not/might not(可能不)。
如:
(1)It can’t/couldn’t be the headmaster. He has gone to America. 这不可能是校长,他去美国了。
(2)He may not/might not know the scientist. 他也许不理解那位科学家。
3.疑问句中用 can/could (能……?)。
如:
(1)Could he have finished the task? 他可能把任务完成了吗?
(2)Can he be at home now? 他现在能在家吗?
注:以上三种句式中情态动词的语气按水准都是依次递减的。Might, could 并非 may, can 的过去式,而表示语气较为委婉或可能性较小。
(二)情态动词表推测的五种时态
1、对现在或一般情况的推测,用“情态动词 + be”,如:
(1)He can’t ( couldn’t ) / may ( might ) not be at home at this time. 这个时候他不可能/可能不在家。
(2)Mr. Bush is on time for everything .How can ( could ) he be late for the opening ceremony ?
布什先生一向准时,这次开幕式他怎么可能迟到呢?
2、.对过去情况的推测,用“情态动词 + have +过去分词”。
如:
(1)It must / may / might / could have rained last night .The ground is wet. 地湿了,昨晚肯定/可能/也许下雨了。
(2)The door was locked. He can ( could ) not / may ( might ) not have been at home . 门锁着,他不可能/可能不在家。
(3)Can / Could he have gotten the book? 难道他找到书了吗? 3、.对将来情况的推测,用“情态动词 + 动词原形”。
如:
(1)She must / may / might / could arrive before 5. 5:00 前她一定/可能/也许到。
(2)She must/may/might/could walk miles and miles among the hills without meeting anyone.
她一定/可能/也许会在山里一连走好几英里而遇不到一个人。
4、对现在或将来正在实行的事推测
如:
He must / may / might / could be listening to the radio now. 他一定/可能/也许正在听收音机。
5、对过去正在发生的事推测
如:
They must have been watching football all night yesterday.昨天一整夜他们肯定在看足球比赛。
说明:
一、can/may /could /might/ought to+动词原形,皆可表示对现在或将来情况的推测,但语气没有 must 强烈。此时动词大多为连系动词(尤其对现在情况推测)。
比较:
You have worked hard all day.You must be tired.你辛苦了一整天,一定累了。
I don’t
know where she is ,she may be in Wuhan。我不知道她在哪儿,也许在武汉 He must be staying there.他现在肯定呆在那儿 He must stay there。他必须呆在那儿 二、may/can/might/could+have done 也能够表示对过去事情的推测,但语气显得不那么肯定。
比较:
The road is wet. It must have rained last night.地面是湿的,昨晚一定下雨了。
Why did you throw the bottle out of the window? You could have hurt somebody. 你为什么向窗外扔瓶子,你可能会砸伤别人的。
考点三 :
情态动词+have done ----- 推测语气 1. must+have+done 表示对过去事情的肯定推测,译成“一定做过某事”,该结构只用于肯定句。如:
1). It must have rained last night, for the ground is wet. 昨晚一定下雨了,因为地面还是湿的。
2). You must have been mad to speak to the servant. 你和仆人说话,一定是发疯了
2.can"t+have+done 表示对过去事情的否定推测,译成“不可能做过某事”。如:
1). Mr. Smith can"t have gone to Beijing, for I saw him in the library just now. 史密斯先生不可能去北京了,我刚才还在图书馆见过他。
2). Mary can"t have stolen your money. She has gone home. 玛丽不可能偷你的钱,她回家去了。
3.can+have+done 表示对过去行为的怀疑,用于疑问句,译成“可能做过……吗?”。如:
1). There is no light in the room. Can they have gone out? 屋里没有灯,他们可能出去了吗? 2). There is nowhere to find them. Where can they have gone? 到处找不到他们,他们可能到什么地方去呢? 4.may+have+done 表示对发生过的事情的推测,意思是“可能已经”或“也许已经”。如:
—What has happened to George?—I don"t know. He may have got lost. —乔治发生了什么事?——我不知道,他可能迷路了。
注意:“might+have+done”表示对过去事情的推测,might 与 may 意思相同,但可能性更小。
----- 虚拟语气 1.“could+have+done”是虚拟语气,表示对过去事情的假设,意思是本来能够做某事而没有做。如:
He could have passed the exam, but he was too careless. 本来他能够通过考试,但是他太粗心。
2.“would+have+done”虚拟语气,表示对过去事情的假设,意思是“本来会做”。如:
1). I would have told you all about the boy"s story, but you didn"t ask me. 我本来会告诉你这个小男孩的故事,但是你没有问我。
2). Without your help, I wouldn"t have achieved so much. 没有你的协助,我是不会取得如此大的成绩。
3.“might+have+done”多用于虚拟语气结构中,表示“本可能做而实际上未做”。可能性极小。如:
1). He might have given you more help, even though he was busy. 他或许会多给你一些协助,即使他很忙。
2). She might have achieved greater progress, if you had given her more chances. 如果你多给她点机会,她可能已经取得更大的成绩。
4.“should/ought to+have+done”意思是“本来应该做某事,而实际没做。” “shouldn"t/ought not to+have+done”表示本来不应该做某事,而实际做了。含有指责对方或自责的含意。如:
1). Tom, you are too lazy. The work should have been finished yesterday. 汤姆,你太懒惰了,这项工作本来应该昨天就做完的。
2). Look, Tom is crying. I shouldn"t have been so harsh on him. 看,汤姆哭了,我本来不应该对他如此严厉。
3). I ought to have gone home last Sunday. 我理应上星期日回家。
4).You ought not to have given him more help. 你不应该协助他那么多。
5.“need+have+done”表示本来需要做某事而没有做。“needn"t+have+done”则表示“本来不需要做某事而做了”。如:
1).I needn"t have bought so much wine—only five people came. 我本来没有必要买这么多酒,只来了五个人。
2). He need have hurried to the station. In that case, be wouldn"t have missed the train. 他本来需要快点去车站,那样的话,他就不会误了火车。
补充:
1)would like to have done sth 本打算做某事 I would like to have read the article, but I was very busy then. 2)would rather +have done 当时宁愿做了 或没做 I would rather have refuse his offer