现代文阅读。 ⑴在浮冰成群的南大洋栖息着南极鳕鱼、松浮鱼、蛇齿鱼,南极多斑鱼等

题型:阅读理解与欣赏

问题:

现代文阅读。

       ⑴在浮冰成群的南大洋栖息着南极鳕鱼、松浮鱼、蛇齿鱼,南极多斑鱼等100多种鱼类,这些鱼鱼体小,一般体长只有25厘米,生长速度缓慢、多数系底栖性鱼类。

       ⑵人的血清在-0.56℃就会冻结,一般鱼类也大致相同。但是,冬天生活在南大洋中的鱼类却能经受-2℃左右的低温而安然无恙。海水的冰点约为-1.85℃,为什么南极鱼的血清在这一温度下却不会冻结呢?原来,在这些鱼的血液中存在着一种抗冻糖蛋白。有趣的是,一到夏天,随着海水温度的上升,这类鱼的脑垂体将会自己调节,使血液中不再产生抗冻糖蛋白。

       ⑶70年代,美国加利福尼亚大学费尔教授从南极的一种鳕鱼的血液中,分离出8种分子量不同的抗冻糖蛋白,发现它们不同程度地具有使水难以冻结的本领。科学家经过实验表明,如果将抗冻糖蛋白从南极鱼的血液中除去,那么它的血液与一般血液没有多大区别,也会在同样的温度下结冰。

       ⑷抗冻糖蛋白是一种相对分子质量非常大的物质,即使溶解的质量稍多些,摩尔浓度(单位体积的溶液中所含抗冻糖蛋白的个数)也是非常低的,而血液基本上仍旧保持着相同的张力。那么,为什么抗冻糖蛋白的浓度如此之小,却能使血液的凝固点发生这样大幅度的下降呢?显然,这一事实用传统的“溶液的凝固点降低理论”是无法解释的。费尔教授等认为,这是因为抗冻糖蛋白分子能挤入互相靠近的两个细微冰晶体的间隙中,从而阻止了冰晶体的生长。即抗冻糖蛋白分子吸附于界面,阻止了水分子向冰晶体方向移动,使凝固点大幅度降低。

       ⑸因此,南极鱼不怕冻。

1.本文的说明内容是:                                                                         

2.本文第二段划线句采用了                                 的说明方法,它的作用是什么?

                                                                                                                                              

3.本文第三段加粗的字“经过实验”不能去掉,为什么?

                                                                                                                                              

4.指出本文的说明顺序,并用波浪线在原文中划出说明对象特征的句子。

                                                                                                                                               

5.水的冰点是0℃,在第二段中提出“海水的冰点约为-1.85℃”,为什么?根据你掌握的知识,结合选文找出能解释这一现象的一句。

                                                                                                                                              

考点:说明文阅读说明方法说明顺序
题型:阅读理解与欣赏

具有社会行为的动物群体中,往往是年长者为“首领”         ( )

题型:阅读理解与欣赏

公元前6世纪末,雅典克利斯提尼改革用10个地域部落代替了4个血缘部落。公元前3世纪晚期赢政在统一全国基础上用郡县制取代了分封制。二者的共同之处是(    )

A.打击了贵族政治

B.推动了社会转型

C.有利于中央集权

D.巩固了新兴地主阶级的统治

题型:阅读理解与欣赏

下面一段文字中加粗的词语,有的必须删去,有的不能删去,请把它们找出来,将序号分别写在下面的横线上。

  11月28日,纪念朱德元帅诞辰120周年暨共和国元帅授勋50周年座谈会在北京举行。

  座谈会①热烈的气氛②进行。与会者深切缅怀了共和国元帅为中 * * 的独立与解放所建立的不朽功勋,③我国社会主义革命和建设事业所做出的伟大贡献,以及④元帅爱国爱民、廉洁奉公、鞠躬尽瘁以及⑤死而后已的高尚品质和英勇顽强、百折不挠、生命不息、战斗不止的革命精神。

  学习⑥弘扬老一辈革命家的优良传统,是构建和谐社会的需要。正如与会者体会的那样:在当前构建和谐社会的关键时期,再一次了解朱德元帅的生平事迹,是一种心灵上的陶冶和净化,对于⑦提高我们的精神修养和政治觉悟,推动各项工作的开展,⑧都十分有益。

(1)必须删去的是:____________________。

(2)不能删去的是:____________________。

题型:阅读理解与欣赏

阅读理解。

     In Western countries people have been using the installment plan since the first half of the twentieth

century. Today, a large number of families in Great Britain buy furniture, household goods and cars by

installments. In the U. S., the figure is much higher than in Great Britain, and people there spend over 10

percent of their income on the installment plan.

     The price of an article bought on installments is always higher than the price that would be paid by cash.

There is a charge for interest. The buyer pays one quarter or one third of the price as a down payment when

the goods are delivered to him. He then makes regular payments, weekly or monthly, until the full price is paid

up. The legal ownership of the goods remains with the seller until the final payment has been made.

     Installment buying has advantages and disadvantages. It can help couples with small incomes to furnish

their homes and start housekeeping. It increases the demand for goods, and in this way helps business and

employment. There is, however, the danger that when business is bad, installment buying may end suddenly,

making business much worse. This may result in a great increase in unemployment. If the people on the

installment plan lose their jobs, they will probably not be able to make their payments. If great numbers of

people are not able to pay their installment debts there is a possibility that businessmen cannot collect their

debts and will therefore lose money. If businessmen lose money or fail to make a satisfactory profit, it

becomes more likely to have a depression. This is why, in some countries, the government controls the

installment plan by fixing the amount of the down payment and installments to discourage people from

buying more than they can pay for on the installment plan.

1. Which of the following is NOT true about the installment plan? [ ]

A. A lot of British families use the installment plan.

B. More than 10 percent American families buy things on installments.

C. Americans depend more on installment than British people do.

D. Americans spend one tenth of their income on installment buying.

2. Goods bought on installments are more expensive than goods bought by cash because _____. [ ]

A. the buyer has to pay extra money as interest

B. the delivery of the goods charges extra money

C. the buyer has to pay a down payment

D. the service offered by installment plan charged extra money

3. What will happen to a buyer if he fails to make the full payment for an item bought on installments? [ ]

A. He might lose his job.

B. He will stop owning the item he has bought.

C. He will have to sell what he has bought.

D. He will go into debt.

4. The advantage of installment buying might include all the following EXCEPT that _____. [ ]

A. purchasing power is strengthened

B. employment might be increased

C. people develop a good habit of saving money

D. young couples are able to furnish their homes

5. In some countries, the governments control the installment plan to _____. [ ]

A. increase employment

B. avoid depressions

C. ensure that businesses make good profits

D. ensure that people can pay for what hey buy

题型:阅读理解与欣赏

以下有关报告叙述不正确的是()。

A.报告是一种搜集、研究事实的人与由于某种目的而要求看报告的人之间的信息或建议的交流形式

B.报告最终作用通常是作为决策和行动的基础

C.所有的报告都是结构完整的正式文书,其写作意图无非是记录信息、告知情况或影响他人

D.标题目的在于向读者提供一个关于该报告所涉及领域的提示或概要性认识

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