英语语法之【ought,should,must,haveto,need表示义务...

1、教育精品资料ought ， shouldmust ， have to ， need 表示义务139 ought 的各种形式140 should 的各种形式141 ought should与 must 和 have to 的比较142 ought should与进行式连用143 ought should与完成式连用144 must和 have to的各种形式145 肯定句中 must 和 have to 的区别146 need not和 must not用于现在时和将来时147 need not， must not和 must 用于现在时和将来时148 need 的各种形式148 节 C 。14

2、9 表示无义务的各种形式但是，关于neednt 在间接引语中的用法，参见上面第150 need not 与其他各种形式的区别151 must ， have to 和 need 用于疑问句152 neednt+ 完成式153 neednt have （ done ）和 didnt have need （ to do ）的比较 -154 neednt ， could 和 should+ 完成式155 need 意指 require （需要）139 ought 的各种形式ought 是情态动词。（参见第 107节 B。）ought 没有其他形式，可用于现在时以及将来时。用于过去时则位于动词过去式之后

3、或不定式的完成式之前：I ought to write to him today tomorrow 我今天明天应该给他写封信。I knew I ought to write to him 我那时知道我应该给他写封信。She said I ought to write她说我应该写。I know knew that I ought to have written 我知道那时知道我该写的。否定式：ought not/oughtn't疑问式：ought I ？等否定疑问式： ought I not ？ oughtn't I ？等ought 与带 to 的不定式连用。为了提醒学生这一点，

4、常称之为 ought to 。问句或话语中用 ought to 的时候，可以用 should 来回答；用 should 的问句或话语 也可以用 ought to 回答： You ought to put in central heating Yes， I suppose I should 你应该装上暖气。是的，我应该装。140 should 的各种形式should 也是情态动词。与 ought 的各种形式相同， should 可用于现在时以及将来时。如位于动词过去式之后时，也可以用于过去时。在上文的各例句中 should 可代替 ought to 使用。否定式： should not shou

5、ldn't疑问式： should I ？等否定疑问式： should I not ？ /shouldn't I ？等should 后面带没有to 的不定式（即动词原形）。should 和 ought 用于表示义务时通常意思是同样的，但should 是较为常用的形式。在会话中 should ought to 常可单独使用，此时动词不定式省略而不说出： You should paint/ought to paint your door Yes， I know I should I know I ought to 你应当油漆下你的门。对，我知道我该这样做。141 ought shou

6、ld 与 must 和 have to 的比较A 用法的不同1 ought should 表示主语的义务或责任：You should send in accurate income tax returns 你应当寄去准确的个人所得税报表。或指出个正确、明智的动作：They shouldn't allow parking here ； the street is too narrow 这儿不该允许停车；马路太窄了。This word is spelt wronglyThere should be another s这个字拼写错了，还应该有个“s ”。这不像must那样牵涉到说话人的权威，

7、也不像 have to那样牵涉到外界权威（参见 第 145 节），仅仅牵涉到良心或见识的问题：Pianist to pupil ： You must practise at least an hour a day 钢琴师对学生说：你每天最少要练习一小时。Pupil to musical friend ： I have to practise an hour a day ！学生对爱好音乐的朋友说：我每天不得不练习一小时！Musical friend ： You ought to should practise for more than an hour 爱好音乐的朋友说：你应该每天练习不止一小时

8、。2 ought/should 与 must 和 have to 之间的又一区别在于，用 must 和 have to 时通 常给人的印象是一种义务正在被履行或将被履行。主语为第一人称时尤其是这样，而其他人称为主语时也常是这样。但ought should 则不使人特别感到义务正在或将要被履行。它时常给人义务不在或不将得到履行的印象，在第一人称主语后更是如此。如果一位驾驶员说I ought to should go slowly here ； it's a built-up area（我是该在此慢行的，这是一个建筑物密集的地区），这通常这意味着他不想要放慢车速。如果他真的要放慢车速，他会

9、说 I must go have to go I will have to goslowly here 。同样，如果某人说We must have a party to celebrate yourengagement （我们必须举办一个聚会来庆祝你的订蜡之喜），他的朋友们有相当理由相信 会举行聚会的，但如果他说 Weshould have a party就不是非常确定无疑的事了，他说 话的语气或表情可能表示不可能举行聚会。B 用法中类似的地方1 should （但不是 ought ）可以用于正式通知或书面文告等：Candidates should be prepared to answer

10、questions on 应试者应有准备回答方面的问题。Intending travellers should be in possession of the following documents准备去旅行的人应备有以下的证明文件On hearing the alarm bell , hotel guests should leave their rooms听至U警报铃声后，饭店的旅客必须离开各自的房间在这里可以用 must 而不改变句子的意思，但在此should 表示义务的口气更缓和些。2 ought 和 should 可表示忠告：You ought to should read this

11、 It's very good 你应该读一下这个。它写得很好。但在语气较重的劝告中用 must 比较好：You must read this It's marvellous ！你必须读这个。写得精彩极了！142 ought should 与进行式连用ought should 与进行式连用时表示主语没有履行其义务，做了愚蠢、鲁莽的事等或做事不明智、不慎重等：He ought to be studying for his exam He shouldn't be spending all his time on the beach 他本该正在学习以备考试。他不该把他的全部时

12、间都在海滩上度过。 We should be wearing seat belts 我们应该系好安全带。（但我们没有系安全带。）I shouldn't be telling you this It's supposed to be a secret 我不应该告诉你这件事。这是个秘密。143 ought should 与完成式连用这个结构用来表示没有覆行义务或不明智地忽略了该做的事。在否定式中这一结构表示从前发生的、错误的或愚蠢的事。You ought to have told him that the paint on that seat was wet你本应该告诉他椅子上的油

13、漆还没有干。You should have turned his omelette ； he likes it turned 你本应该给他摊的鸡蛋翻个身的；他喜欢吃两面都煎透的摊鸡蛋。They ought to have stopped at the traffic lights他们本应在红绿灯处停下。She shouldn't have opened the letter ； it wasn't addressed to her 她不应该拆开信，信封上写的不是她的名字。The Emergency Exit doors shouldn't have been block

14、ed 紧急出口的门本来不应被堵死。144 must 和 have to 的各种形式A mustmust是情态动词。（参见第107节B。）它用于现在时和将来时。否定式： must not /mustn't疑问式：must I ?等否定疑问式：must I not ? / mustn't I ?等过去时用had to代替。must与不带to的不定式（即动词原形）连用。它可表示义务和语气较强的劝告：Father： You must get up earlier in the morning . 父亲： 你早晨必须起早一点。 （义务）You must take more exercis

15、e . Join a squash club你应该多锻炼。参加一个壁球俱乐部吧。（劝告）B have to义京无义务说话人外部的权力的权力niU5tshall，will Itm toshan't / wmi't havic 1o现在时musthave to *don't / iloesn'l have to*have酣)to*hadn't ( got ) to*过去时had tohad todidn't hsvie tohadn't (驶 J to*请见下面C。C带星号的have to各形式间的区别have to （不带got）与否定式d

16、on't /doesn't have to 是表示习惯性行动的正确形 式，但也可以用于表示一次性行动。在美国英语中是普遍使用的。have （got） to和haven't （got） to只用于表示一次性行动：But I don't have toTom： I have to go to work every day except Sundaywork a full day on Saturday 汤姆：除了星期天外我必须每天去上班，但星期六我不必干一整天。但在星期天他可以说：I'm glad I haven't （got to go to wo

17、rk today I'm glad I don't have to go to work today 我真高兴，今天不必上班。过去式didn't have to既可表示过去的习惯，也可表示一次性行动。hadn't （got ） to 多用于表示一次性行动。didn't have to 是较为普遍的形式。have to 在肯定句中表示“义务”。have to 在否定句中表示“无义务”。这种意思也可由 need not ， don't need 等来 表示。（参见第149 节。）145 肯定句中 must 和 have to 的区别A must 表示

18、由说话人加予的义务：Mother ： You must wipe your feet when you come in 母亲：你进屋前必须先蹭脚。have to 则表示外界的义务：Small boy ： I have to wipe my feet every time I come in小男孩：我每次进屋前都得先蹭掉鞋上的土。B 第二人称的例句1 说话人的权威Mother ： You must wear a dress tonight You can't go to the opera in those dreadful jeans 母亲：你今晚必须穿一条礼服裙衣。你可不能穿着那些难

19、看的牛仔服去歌剧院。Employer： You must use a dictionary I'm tired of correcting your spelling mistakes 雇主：你必须用字典。我厌烦给你改拼写错误了。Doctor ： You must cut down on your smoking 医生：你必须少吸烟。2 外界的权威You have to wear uniform on duty ， don't you ？你在值班时必须穿制服，是吗？You have to train very hard for these big matches， I supp

20、ose 我想，为参加这些大赛你必须刻苦训练。You'll have to get up earlier when you start work， won't you ？你开始上班时，就要早起一些了，是吗？You'll have to cross the line by the footbridge你必须从天桥过马路。C 第三人称的例句这时 must 主要用于书面指令或指导：Railway company ： Passengers must cross the line by the footbridge铁路公告：旅客必须由天桥过马路。Office manager : S

21、taff must be at their desks by 9： 00。办公室经理：工作人员必须在 9 : 00前到达各自的办公桌前。Regulation ： A trailer must have two rear lamps 规章：拖车必须有两盏后灯。只不过是讲述或评论他人的义务时，则用 have to ：In this office even the senior staff have to be at their desks by 9： 00.在这个办公室，就连高级职员也要在 9 : 00前到达他们各自的办公桌前。She has to make her children's

22、clothes She can't afford to buy them 她必须自己给孩子们做衣服穿。她买不起。They'll have to send a diver down to examine the hull他们必须派潜水员下水去检查船体。如果用 must 代替上面例子中的 have to ，就可能意指说话的人有权下命令这样做。但 must 可用于表示说话人对某种责任、义务是赞成或同意的：A driver who has knocked someone down must stop 撞人的司机必须停车。（说话人认为这是司机的责任。）或表示说话人很强烈地认为应该这样：S

23、omething must be done to stop these accidents 必须采取某种措施以防止这些事故。D 第一人称的例子第一人称为主语时，must和have to二者之间的差别不那么重要，常常两种形式都 可以用：Typist ： I must will have to buy a dictionary 打字员：我必须去买一本字典。Patient ： I must have to/will have to cut down on my smoking患者：我必须减少吸烟。但在表达习惯时， have to 更好：I have to take two of these pill

24、s a day我必须每天吃两片这种药。某事对说话人很急迫，或被说话人认为很重要时，则以用 must 为好：I must tell you about a dream I had last night我必须把我昨晚做的梦告诉你。Before we do anything I must find my cheque book 在我们干任何事之前，我必须先找到我的支票簿。E 其他例句（各种人称）You must come and see us some time 你有空一定来看我们。（这是一种常用的随便的邀请方式。）The children have to play in the street ti

25、ll their parents come home孩子们不得不一直在马路上玩到他们的父母回到家里为止。This sort of thing must stop ！必须制止这种事！（说话人或者有权或者对此事感觉强烈。）You must write to your uncle and thank him for his nice present你必须给你叔叔写信并感谢他给你的很好的礼物。If there are no taxis we'll have to walk如果没有出租车了，我们就不得不步行。If your father was a poor man you'd have

26、 to work如果你父亲是个穷人，你就不得不工作了。We have to walk our dog twice a day 我们每天得遛两次狗。注意如下常见的例子：In shop window ： Closing down sale ！ Everything must go ！商店橱窗里的告白：关门大甩卖！卖完为止！F 表示过去的义务的肯定句用 had to 表示过去的义务时，而且说话人本身的权威和外界的权威无法区分时，只可用一个形式，即 had to ：I ran out of money and had to borrow from Tom 我没钱花了，不得不向汤姆借钱。You had

27、to pay duty on that ， I suppose ？我想你不得不为那个付了税吧？There were no buses so he had to walk 没有公共汽车，所以他只好走着去。146 need not 和 must not 用于现在时和将来时need not 可用于现在时和过去时。各人称的形式都一样。（参见第148 节。） neednot 表示“无义务”。它表示说话人允许不去做某事，或仅仅表示某事并非必要：Employer ： You needn't make two copies One will do雇主：你不用打印两份。一份就够了。Give them t

28、his cheque They needn't send me a receipt 把这张支票给他们。他们不用给我送来收据。You needn't change ( your clothes ) Just come as you are 你不用换(衣服)了。就穿着现在穿的衣服来吧。must not 表示否定的义务，即说话人叫你不要如何或是特别强调地劝告你不可如何：You mustn't repeat this to anyone 你不能把这件事告诉任何别人。Notice in shop ： Staff must not smoke when serving custom

29、ers 商店通告：工作人员在为顾客服务时一律不许抽烟。You mustn't leave your car unlocked This place is full of thieves 你千万不能不锁车门就离开。这地方遍地是小偷。147 need not ， must not 和 must 用于现在时和将来时Doctor ： You needn't go on a diet ； but you must eat sensibly and youmustn't overeat 医生：你不必节食，但要饮食有度，不能吃得过饱。Zoo notice ： Visitors mus

30、t not feed the animals 动物园通告：参观者不得给动物投喂食物。Railway notice ： Passengers must not walk on the line 铁路通告：旅客不得在铁路线上行走。You mustn't drive fast There is a speed limit here 你不能开快车。这地方有速度限制。You needn't drive fast We've plenty of time 你不必开得快。我们时间足够。You needn't strike a match I can see well enou

31、gh 你不用划亮火柴。我可以看清。You mustn't strike a match This room is full of gas 你不能划火柴。这屋里满是煤气。School notice ： The lifts must not be used during Fire Drill学校通告：在消防演习期间禁止使用电梯。You mustn't wear that dress again You look terrible in yellow 你别再穿那套裙装了。你穿黄色难看极了。Teacher ： You needn't read the whole book bu

32、t you must read the first four- chapters 老师：你们不必把整本书全读完，但必须读完前四章。You must cut down that dead tree or it will fall on your house你必须把那棵死树砍了，否则它会倒在你的屋顶上。Doctor ： You mustn't take more than two of these pills at once Three mightbe fatal 医生：这些药你每次服用时不得超过两片。服三片就可能有生命危险。Doctor （to patient's wife）：

33、If the pain has gone he needn't take any moreof these 医生（对患者的妻子）：如果疼痛已经消失了，他就不必再服这些药片了。148 need 的各种形式A need 既可以作助动词，也可以作普通动词。用为助动词时，它是半情态动词，即它既有情态动词的形式又有普通动词的形式。它的情态动词的形式有need 或 need not needn't ，可用于各种人称的现在时、将来时和间接引语中。（参见下面 C 节。）疑问式： need I ？等否定疑问式： need I not ？ needn't I ？等 need 以上述各种形式

34、变化时，后面接不带 to 的不定式（即动词原形）。B need 为助动词时一般只在下述情况下可以用于肯定式：当一个否定句或疑问句由于前面加上一个短语而使其中的否定动词或疑问动词变成肯定的意思时：I needn't wear a coat I don't suppose I need wear a coat 我不需要穿外衣。我认为我不需要穿外衣。Need I tell Tom ？ Do you think I need tell Tom ？我需要告诉汤姆吗？你认为我需要告诉汤姆吗？有时在相当正规的英语中，它也与 hardly scarcely 或 only 连用：I need h

35、ardly say how pleased we are to welcome Mr X 我几乎不用说我们是多么高兴欢迎X先生的来到。（我无需说）You need only touch one of the pictures for all the alarm bells to start ringing 你只要摸一下其中的一幅画，所有的警铃就都会响起来。（如果你摸到其中的一幅 画，所有的铃）C needn't在直接引语中可以不必改变：You needn't pay till the 31st , 'he says /said.他说：“你到31号才需要付钱。”相当于：H

36、e says/said I needn't pay till the 31st他说我到31号才需要付钱。（参见第325节C。）D need变否定形式时也可像普通动词一样变化，如下面第149节所示。表中也列出了相应的have to形式。关于疑问句形式参见第151节。need与will /shall , do/does/did等助动词连用时应当用带to的不定式，有时 称为need to以引起学生注意。149表示无义务的各种形式说话人的权威外界的枳威将来时iteed notshan't / wilt 蜥乳 toshan't / won't Ww io现在时Med he

37、t±in't / doesn't need todon't，doesn't have to/ hadn't gpt to过吉时（蓼见第1切节）didn't used to didn't ha/e tohadn't gpt to但是，关于needn't在间接引语中的用法，参见上面第 148节C。 won't have toshan't won't need to=shan'tdon't doesn't need to=don't doesn't hav

38、e todidn't need to= didn't have to （但 didn't have to 更常见）完全同义从上面的表格中可以看出，与haven't hasn't got to 和 hadn't got toneed 的形式是不存在的。150 need not 与其他各种形式的区别A1 如前所述， need not 表示说话人的权威或劝告：You needn't write me another cheque Just change the date and initial it 你不必给我另开一张支票。你只需改一下日期并签

39、上你姓名的第一个字母。I'm in no hurry He needn't send it by air He can send it by sea 我不着急。他不必用航空寄来。海运过来就行。You needn't do it by hand I'll lend you my machine 你不必用手缝。我把缝纫机借给你。You needn't call me Mr Jones We all use first names here 你不用管我叫琼斯先生。我们这里都只叫名字。College lecturer ： You needn't type

40、 your essays but you must write legibly 大学教师：你们不必把文章用打字机打出来，但必须字迹清楚。2 其他表示外界权威的形式：Tom doesn't have to wear uniform at school汤姆在学校不一定要穿校服。We don't have to type our essays but we have to write legibly我们的文章不一定要打出来，但字迹一定要清楚。When I'm an old age pensioner I won't have to pay any more bus f

41、ares等我到领取养老金的时候，我坐公共汽车就不用买票了。Ann hasn't got to go doesn't have to go to this lecture Attendance isop- tional 安不一定非去听讲。那讲座是可去可不去的。When I have a telephone of my own I won't have to waste time waiting outside these wretched telephone boxes 等我自己有了电话，我就不用等在讨厌的电话亭外而浪费时间了。Ann doesn't have t

42、o cook for herself She works at a hotel and gets all hermeals there 安不用自己做饭吃。她在一家饭店工作，在那里用餐。3 然而，有时need not 也可以用于表示外界权威，以代替 won't don't need to或 won't don't have to等各种形式。这种用法尤其普遍地用于第一人称：I needn't won't don't have to type this report today Mr Jones said that there was no h

43、urry about it 我今天不必把这个报告打出来。琼斯先生说这份报告不急着要。请注意，虽然need not 可用来表示将来的习惯性动作：I'm retiring After Friday I need never go to the office again我就要退休了。星期五之后我就再也不必到办公室去了。但不能用 need not 表示一个现在的习惯性动作：I get on at the terminusI don't have to queue for my bus我用不着排队等公共汽车。我在首发站上车。（这里不能用 neednot 。）B 过去时如need用于过去时

44、，说话人的权威和外界权威之间的差别就消失了，因而我们可任 意运用以下三种形式： didn't have to ， didn't need to 和 hadn't got to 。这几种用法 不存在含义上的差别，但hadn't got to 不常用于表示习惯性动作。 didn't have to是最常用的：I didn't have to wait long He was only a few minutes late 我没等太长时间。他只迟到了几分钟。When he was at university he didn't have to

45、need to pay anything for his keep， for he stayed with his uncle 他读大学时不需要付食宿费用，因为他与他的叔父住在一起。151 musthave to 和 need 用于疑问句向有权威的人询问外界权威将来时 must I ?等 坡虱I7等现在时 must I 7等加冢1 ?等shall 吊 we have io ? 雨HM 等+havs> to ?do I 等+toe t。7does he等十1面化to ? have I 等+(gpt > to ? has %等 4 C) to ?shall I J we need 1o

46、 ?will he 等+iiEd 小?do I 等+need to 7 does he 等+nc&ltci ?过去时dud be 等十havis to ?did 屉 等tneedki ?liatl he 等gol t口 7need?和must?都意味着说话的对方是有关的权威。need?还包含着说话人希望得到否定回答的含义： Must I go , moth- er ?和Need I go , mother ?含义相同，但在后 一问句中，说话人希望他的母亲回答说“不"。need的另一种疑问式do I need ?等也有同样的用法。注意以下各种可能的回答：-Shall I hav

47、e to go?Yes, you will . /No, you won't .我必须去吗？一是的，必须去。/不，不必去。 Have I got to go ?Yes, you have . /No, you haven't我必须去吗？一是的，必须去。/不，不必去。 Does he have to go ?Yes, he does . / No, he doesn't他必须去吗？是的，必须去。/不，不必去 Need I go ？ Yes， you must No， you needn't我需要去吗？是的，必须去。不，不需要去。 Must I go ？ Yes，

48、you must No， you needn't我必须去吗？是的，必须去。不，不需要去。152 needn't+ 完成式这个结构用来表示虽然不必要但却已完成的动作：I needn't have written to him because he phoned me shortly afterwards我本来不需要给他写信，因为不久之后他就给我打了电话。（但我的确写了，因而浪费了时间。）You needn't have brought your umbrella for we are going by car你本来不用带雨伞，因为我们将要坐车去。（但是你却多余地带

49、了伞。）He needn't have left home at 6:00； the train doesn't start till 7:30他本不必 6 点就离开家；火车7 点 30 分才出发。（因此他要等一个小时。）153 needn't have （ done ）和 didn't have need （ to do ）的比较A needn't have done 意指没必要干某件事但多余地干了，即浪费了时间：You needn't have watered the flowers ， for it is going to rain 你本不

50、必浇那些花，因为就要下雨了。（你浪费了时间。）You needn't have written such a long essay The teacher only asked for300 words ， and you have written 600你本不必写这么长的文章。老师只要求写 300个字而你却写了 600个字。He needn't have bought such a large house His wife would have been quite happy in a cottage 他没必要买这么大一所房子。他的妻子住在一个小房子里也会感到很满意的。（浪费了钱）You needn't have carried all these parcels yourself The shop would havedelivered them if you had asked them 你本来没有必要自己拿着这些大包小裹的。要是当时你跟商店说一声，他们就会把东西送来的。B didn't have need to do 意指不一定非干某事，而通常也并没有这样做：I d