专项突破:2021年考研英语排序题模拟试题(2020-10-16)

发布时间:2020-10-16


最近,有小伙伴在询问最后阶段,考研英语该如何备考才最有效。最后阶段,我们应该将备考的重点放在复习和了解考试上,多去练习历年真题和模拟试题。下面,51题库考试学习网为大家带来考研初试的一些模拟试题,一起来看看吧。

Passage 7

Directions: For question 1—5, choose the most suitable paragraphs from the list A—G and fill them into the numbered boxes to form a coherent text. Paragraphs A and G have been correctly placed.

[A] A GOOD unit of measurement, writes Robert Crease, must satisfy three conditions. It has to be easy to relate to, match the things it is meant to measure in scale (no point using inches to describe geographical distances) and be stable. In his new book, “World in the Balance”, Mr Crease, who teaches philosophy at Stony Brook University on Long Island and writes a column for the magazine Physics World, describes mans quest for that metrological holy grail. In the process, he shows that the story of metrology, not obvious material for a pageturner, can in the right hands make for a riveting read.

[B] In response the metre, from the Greek metron, meaning “measure”, was ushered in, helped along by French revolutionaries, eager to replace the Bourbon toise (just under two metres) with an allnew, universal unit. The metre was to be defined as a fraction of the Paris meridian whose precise measurement was under way. Together with the kilogram, initially the mass of a decaliter of distilled water, it formed the basis of the metric system.

[C] Successful French metrological diplomacy meant that in the ensuing decades the metric system supplanted a hotchpotch of regional units in all bar a handful of nations. Even Britain, long wedded to its imperial measures, caved in. (Americans are taking longer to persuade.) In 1875 Nature, a British magazine, hailed the metric system as “one of the greatest triumphs of modern civilisation”. Paradoxically, Mr Crease argues, it thrived in part as a consequence of British imperialism, which all but wiped out innumerable indigenous measurement systems, creating a vacuum that the new framework was able to fill.

[D] For all its diplomatic success, though, the metre failed to live up to its original promise. Tying it to the meridian, or any other natural benchmark, proved intractable. As a result, the unit continued to be defined in explicit reference to a unique platinumiridium ingot until 1960. Only then was it recast in less fleeting terms: as a multiple of the wavelength of a particular type of light. Finally, in 1983, it was tied to a fundamental physical constant, the speed of light, becoming the distance light travels in 1/299,792,458 of a second. (The second had by then itself got a metrological makeover: no longer a 60th of a 60th of a 24th of the period of the Earths rotation, it is currently the duration of 9,192,631,770 periods of a phenomenon called microwave transition in an atom of caesium133.)

[E] The earliest known units met the first two of Mr Creases requirements well. Most were drawn from things to hand: the human body (the foot or the mile, which derives from the Latin milia passuum, or 1,000 paces) and tools (barrels, cups). Others were more abstract. The journal (from jour, French for “day”), used in medieval France, was equivalent to the area a man could plough in a day with a single ox, as was the acre in Britain or the morgen in north Germany and Holland.

[F] But no two feet, barrels or workdays are quite the same. What was needed was “a foot, not yours or mine”. Calls for a firm standard that was not subject to fluctuations or the whim of feudal lords, grew louder in the late 17th century. They were a consequence of the beginnings of international trade and modern science. Both required greater precision to advance.

[G] Now the kilogram, the last artefactbased unit, awaits its turn. Adding urgency is the fact the “real” kilogram, stored in a safe in the International Bureau of Weights and Measures in Sèvres, near Paris, seems to be shedding weight relative to its official copies. Metrologists are busy trying to recast it in terms of Plancks constant, a formula which is deemed cosmicly inviolate, as is the speed of light (pending further findings from CERN, anyway). In his jolly book, Mr Crease is cheering them on.

A→1→2→3→4→5→G

以上就是51题库考试学习网为大家带来的全部内容,希望能给大家一些帮助。51题库考试学习网提醒:2021年考研正式报名已经开始,在预报名阶段未来得及报名的小伙伴要注意了。另外,小伙伴们如果还有其他关于考研信息的疑问,也可以留言咨询哦。


下面小编为大家准备了 研究生入学 的相关考题,供大家学习参考。

实验心理学中,挑选被试时最应注意(  )

A.被试数量最好达到30个
B.被试要具有代表性
C.随机选取被试
D.最好选择有经验的被试
答案:B
解析:
实验心理学中,挑选被试时最应注意是要有代表性。保持代表性的最重要办法是随机选取被试,当然还有其他的抽样方式,如分层抽样、系统抽样等。被试的数目要根据实验设计的需要来定,选择被试也根据实验需要,一般情况不选有经验的被试,以免有练习和其他效应的影响。

肝素抗凝血的主要机制是
A.增强抗凝血酶1的活性B.增强纤溶酶的活性 C.抑制血小板聚集D.抑制凝血酶原激活

答案:A
解析:
①抗凝血酶DI由肝脏和血管内皮细胞产生,可灭活FIXa~FXIIa,为最主要的抗凝物质,占凝血酶抑制活性的75%。②肝素是一种酸性黏多糖,主要由肥大细胞和嗜碱性粒细胞产生。肝素具有较强的抗凝作用,但缺乏抗凝血酶III时,其抗凝作用很弱。因此肝素主要通过增强抗凝血酶III的活性而发挥间接抗凝作用(肝素与抗凝血酶BE结合后,可使后者的抗凝作用增加2000倍〉。此外,肝素还可刺激血管内皮细胞释放大量TFPI而抻制凝血过程。

关于二尖瓣关闭不全和二尖瓣狭窄的比较,f误的是
A.从首次风湿热至发病的时间前者比后者i ? B.发生急性肺水肿的几率前者大于后者 C.两者都可出现P2亢进 D.两者都可于心尖部闻及杂音

答案:B
解析:
从风心病至二闭出现症状至少需20年,从急性风湿热至形成二狭至少需2年。②二狭时,血 液从左房流人左室受阻,出现左房高压—肺静脉高压—肺淤血—呼吸困难—发生急性肺水肿的几率大。 二闭时,以左室大为主,稍晚期可出现左房增大,肺水肿发生较晚。③二闭和二狭发生肺动脉高压时,两 者都可出现P2亢进。④二狭时可闻及心尖部隆隆样舒张中晚期杂音,二闭时可闻及心尖部全收缩期吹 风样高调一贯型杂音。

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