The word ?base? in the last paragraph represents. A.a production place B.the initial operation of building aircraft C.a research institute D.a position where to start building 答案:CDADA 9.2008 年 6 月英语六级阅读理解专项训练(1) There is evidence that the usual variety of high blood pressure is,in part,a familiar disease.Since families have similar genes as well as similar environments,familiar diseases could be due to shared genetic influences,to shared environmental factors,or to both.For some years,the role of one environmental factor commonly shared by families,namely dietary salt(i.e.,sodium chloride),has been studied at
Brookhaven National Laboratory.These studies suggest that chromic excess salt ingestion can lead to high blood pressure in man and animals.Some individuals,however,and some rats consume large amounts of salt without developing high blood
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pressure.No matter how strictly all environmental factors were controlled in these experiments,some salt-fed animals never developed hypertension whereas a few rapidly developed very severe hypertension followed by early death.These marked variations were interpreted to result from differences in genetic constitution. By mating is successive generations only those animals that failed to develop hypertension from salt ingestion,a resistant strain(the "R" Strain)has been evolved in which consumption of large quantities of salt fails to influence the blood pressure significantly.In contrast,by mating only animals that quickly develop hypertension from salt,a sensitive strain("S"
strain)has also been developed. The availability of these tow strains permits
investgations not heretofore possible.They provide a plausible laboratory model on which to investigate some clinical aspects of the human prototypes of hypertension.More important,there
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might be the possibility of developing methods by which genetic susceptibility of human beings to high blood pressure can be defined without waiting for its appearance.Radioactive sodium 22 was an important "tool" in working out the characteristics of the sodium chloride metabolism. 1.The study of the effects of salt on high blood pressure was carried out . a.as members of the same family tend to use similar amounts of salt b.to explore the long-term use of a sodium based substance c.because it was proven that salt caused high blood pressure d.because of the availability of chemically pure salt and its derivatives 2.The main difference between "S" and "R" rats is their . a.need for sodium 22 b.rate of matingc.reaction to saltd.type of blood 3.We can infer from the article that sodium 22 can de used to
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. a.control high blood pressureb.cure high blood pressure caused by salt c.tell the "S" rats from the "R" ratsd.determine what a sodium chloride metabolism is like 4.The most beneficial results of the research might be . a.development of diets free of saltb.an early cure for high blood pressure c.control of genetic agents that cause high blood pressured.the early identification of potential high blood pressure victims 5.Which of the statements best relates the main idea of this article? a.When salt is added rats and human beings react
similarly.b.The near future will see a cure for high blood pressure. c.The medical field is desperately in need of research.d.A tendency toward high blood pressure may be a hereditary factor.
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[单选题][A] research[B] operation[C] movement[D] search
[单选题][A] operation[B] production[ C] procession[ D] action
[单选题]16.A. lots ofB.so muchC.a lotD.a ittle
在 x = 0 处可导,则 a , b 的值应为( ) A.a = 2,b = 1 B.a = 1,b = 2 C.a =-1,b =-1
Under __ tree,there is __-|||-old man.-|||-A.a;the;an B.an;the;an C.a;an;an D.an
[单选题]Molish反应为阴性A.甘草酸B.甘草次酸C.A及B两者均有D.A及B两者均无
[单选题]多数为粉末A.皂苷B.皂苷元C.A及B两者均有D.A及B两者均无
[单选题]没有发泡性A.皂苷B.皂苷元C.A及B两者均有D.A及B两者均无
[单选题]无明显熔点A.皂苷B.皂苷元C.A及B两者均有D.A及B两者均无
[单选题]有甜味A.甘草酸B.甘草次酸C.A及B两者均有D.A及B两者均无