二、逻辑关系
考点分析
句子与句子之间的逻辑关系是句子的命脉，博士研究生入学英语考试中的改错题有复合句，做此种类型题时必须要把握整个句子的逻辑关系。逻辑关系错误主要是由肯定与否定、关联词或短语等误用所造成的，考生应多从这方面去查找错误。
（一）逻辑关系词误用
改错题对逻辑关系的考查主要集中在句子之间的关系上，如因果、转折、条件、让步等关系，具体体现在句子间使用的连接词上，其中以因果和转折连接词的误用最为常见。
（二）上下文语义矛盾
上下文语义矛盾是指文章前后所表达的意思不一致，甚至正好相反，即根据上下文的内容，应该是表达肯定或积极意义的地方，却误用了表达否定或消极意义的词；或是与此相反，应该是表达否定或消极意义，却误用了表达肯定或积极意义的词。技巧点拨
（1）画线的句子或短文出现逻辑关系词时注意，是否用法正确。
（2）结合上下文仔细推敲，准确把握前后的逻辑关系。始终牢记文章中各个句子并不是孤立地堆砌在一起，而是相互联系的。
（3）熟悉表示各种逻辑关系的常用关系词及其用法。
典型真题
例1：
If it were only necessary to decide whether to teach elementary science to everyone on a mess basis or to find the gifted few and take them as far as they can go，（1）mass our task would be fairly simple.The public school system，moreover，has no such（2）____choice，for the two jobs must be carried on at the same time.（山东大学2008年）
【名师点评】moreover→however。逻辑关系词误用。前文的few表示否定，而本句中的must be表示肯定，表明上下文的逻辑关系为转折，且用逗号与句子隔开，只能是moreover改为however。
例2：
The total quantity of water is not known，and it is about enough to cover the surface of the globe 7 to a depth of about two and three-quarter kms.Most of it—97%is in the form of the salt waters of the oceans.（南开大学2008年）
【名师点评】and→although。短文中这里的前半句not表示否定，但后面enough to cover...为肯定，因此前后是让步关系，而不是并列关系。故and改成although。
例3：
Governments are also pushing to make air cleaner—see the White House’s move last week to further tighten soot standards.（70）It is perfect，but we’ve had much more success dealing with air pollution than climate change.（北京大学2013年）
【名师点评】（is）not（perfect）。这个句子中有but，可知前后分句形成转折关系。but后面分句表示肯定含义，因此，but前面分句应表示否定含义。
例4：
（71）As of now，it does not include groceries，though Mr.Nave did dismiss that possibility.（北京大学2011年）
【名师点评】（did）not（dismiss）。上下文语义矛盾。句子中间的though表示让步，后面应该表示否定的意味，所以did后应该加not。句意：目前，它（沃尔玛的网站）不包含食品，虽然Nave先生没有忽略这种可能性。
例5：
A S1____
good CV is your passport to an interview and，ultimate，to S2 ultimately
the job you want.Initial impressions are vital，and a badly presented CV
could mean acceptance，regardless of what’s in it.S3____（重庆大学2012年）
【名师点评】acceptance→unacceptance。上下文语义矛盾。前文中的CV是badly presented的，说 明 这 是 不 能 被 接 受 的，否 定 的 意 思。因 此acceptance改 为unacceptance。
实战演练
1.When U.S.soldiers came home after World War II，for example，they dreamed ofbuying houses and starting families.But there was a tremendous boom in home building.____
2.Initial impressions are vital and a badly presented CV could mean acceptance，regardless of what’s in it.____
3.They 
most of their 
salt water，
they return to
birthplaces to spawn and die.
4.“Emotional”motives imply the 
of goods according to 
or subjectivecriteria—the desire for 
，pride，fear，affection 
status.
5.
the teacher will 
mark our English 
for spelling and grammar，
she will be looking for pleasing expression.
6.There was an 
on this street this morning and 
there has been a
of traffic.(https://www.daowen.com)
7.The 
issued an order stating that 
land purchased from thegovernment 
be paid for 
r.
8.Self-image can be 
a tone of voice that is confident，pretentious，shy，aggressive，or exuberant，to name only a few personality traits.
the sound mayindicate the facade or mask of that person，
，a shy person hiding behindan 
front.
9.Most doctors 
said that annual physical examinations were effective
detecting illness in apparently healthy patients，
there is little scientific evidence
support the exams.
10.Two 
factors in teaching a dog to 
are using the same act，
，teaching only one act 
11.When the aerials are down，
your spirit is covered with snows of cynicism and theice of pessimism，
you are growing old，even at 20，
as long as youraerials are up，to catch waves of optimism，there is 
you may die young at 80.
12.Only humans and some primates enjoy color vision.The red flag is black to the bull.Horses live in a monochrome world.Light visible to human eyes，
，occupiesonly a very narrow band 
electromagnetic spectrum.Ultraviolet rays
humans though ants and honeybees are 
them.
13.Humans have no direct perception 
infrared rays 
the rattlesnake 
hasreceptors tuned into wavelengths longer 
0.7 micron.
14.The Black Widow
found in all states 
is most 
in the south 
the west.
15.We knew that it was supposedly run in accordance 
certain rather vague and oftencomplex rules and professional orders.
once we tried finding out exactly
all this money went on，what these highly paid individuals did for it（and with it），and 
the rules and orders influenced them，a curious thing happened.
16.The ash 
a volcano spreads worldwide in a few days and 
in the air foryears.Its effect is 
turn incoming solar radiation into space and 
cool theearth.
17.Formal demography limits its object of study to the measurement of populations
，
the more broad field of social demography studies also analyze therelationships 
economic，social，cultural 
biological processes influencinga population.
18.In a referendum in 1995 voters overwhelmingly rejected 
.Bermuda isBritain’s oldest colony and it 
much of its 
through banking and otherfinancial 
.
19.Today the main economic activities of the family 
in the nature of 
productive may be 
some of its members do in society.
20.Why has inflation proved so mild The most thrilling explanation is，
，a littledefective.Some economists argue that powerful structural changes in the world have
the 
economic models that were based upon the 
link betweengrowth and inflation.
答案解析
1.But→So。逻辑关系词误用。前一句是说二战后返家的士兵都梦想购买房屋、建立家庭，后一句是说出现了建造房屋的热潮，显然前后应该是因果关系，而不是转折关系，故应将But改为So。
2.上下文语义矛盾。前面提到initial impressions（第一印象）非常重要，那么badly presented（外表很差的）简历不管内容如何，肯定是会被拒绝，而不会被接受，原文中acceptance导致了上下文语义矛盾，应将其改为rejection。
3.C。despite是介词，后面一般接名词做宾语，而在句中它后面却跟着一个完整的句子，所以改为连词though。
4.B。本句对“感性动机”进行说明，显然其判断标准也一定不是客观的，应该是主观的subjective，而与subjective相近的词应该是personal（个人的），不是impersonal（不受个人感情影响的）。
5.D。根据行文逻辑，前文not为否定，后面表达的意思与此相反，因此表示并列关系的and应改为表示转折关系的but。
6.B。句中有and连接，不能使用从句。根据句中的现在完成时态可知，此处应该改为since，表示“自从那时”。
7.B。moreover意为“而且”，不符合题意要求。根据句意：……从即日起，向政府购买土地须用金银支付。因此，moreover应改为henceforth。
8.B。此句的内容表明与上文之间为递进关系，而非转折关系。因此，将Yet改成Besides，Also，Moreover或Furthermore等。
9.C。even一词可以做副词、形容词和动词，但是不能作为连接词，因此两个分句之间不能用even连接。其次由于两个分句之间是转折关系，even though又是常用的转折连词词组，因此，在even后面添加though将语法结构补充完整。
10.C。前面谈到两个方面，and和moreover只能用其中的一个，否则语义重复。把and或moreover去掉。
11.C。however作“然而，可是”讲时，较but意味稍弱，且后应跟有逗号，使其与句子的其他部分隔开。因此，将however改为but。
12.A。此前说到哺乳动物中只有人有色彩识别能力，其他哺乳动物都生活在单色的世界中，此句紧接着说人类也不能识别色谱中的所有颜色。可见两者之间是转折关系，说明纵然人们能识别颜色，但也是有限的。因此，therefore应改为however。
13.B。根据上下文，此处意为人类不能识别红外线，这点和响尾蛇不同，它们有自己特殊的感应器，可以识别长于0.7微米的光波。因此，like应改为unlike。
14.B。根据上下文，应选用表示递进关系的and。因此，or应改成and。
15.B。前面指出广告业经营需要遵循一定的规则，这些规定有些模糊，很复杂，但很专业。接着本句提出“出现了怪现象”，两者之间无因果关系，而为转折关系。因此，Therefore应改为But。
16.D。根据上下文的逻辑关系，此处表达的是因果关系，而非转折关系。因此，however应改为thus。
17.B。前后两个分句之间是对比的关系，所以应该用表示对比的从属连词while。因此，when改成while。
18.A。referendum意为“公民投票权”；overwhelmingly意为“压倒一切地”；reject意为“反对”。依据上下文的逻辑关系，不难发现dependence应改为independence。
19.C。将how改成however。however+adj./adv.中的however相当于no matter how，表示让步意义。
20.A。原句是说“通货膨胀率如何温和的原因是负面的”，既然提到了defective，就说明这个现象是负面的，fortunately不符合逻辑，应该改为unfortunately。