问题 问答题

综合问答—叉鱼过程中的物理: 炎热的夏天,小雨和爷爷划船到湖中叉鱼,请你挑选2个场景,用所学的物理知识注行解释:

①感觉在湖中比在岸上凉爽;②划船时,手移动较小的距离,船桨在水中移动较大的距离;③向后划水,船向前进;④叉鱼时,瞄准看到的鱼的下方才能叉到鱼。

(1)解释场景:              (2)解释场景           

答案

解释场景①:(根据公式可知)在质量和吸放热相同时,比热容大的物质温度变化少。水和泥土相比,水的比热容较大,在同样受热时,温度升高得较少,所以感觉在湖中比在岸上凉爽。

解释场景②:使用费力杠杆可以省距离。船桨是费力杠杆,划船时,手加在船桨上的动力比水对船浆的阻力大,所以手只要移动较小的距离,就能使船桨在水中移动较大的距离。

解释场景③:物体间的作用力是相互的。向后划水时,给了水一个向后的力,同时水给船一个向前的力,因此船向前进。

解释场景④:这是光的折射现象。人在空气中看水中的鱼时,水中鱼反射的光从水中斜射到空气中发生折射,折射光线远离法线进入人的眼中,人逆着折射光线看到的是变浅了的鱼的虚像,真正的鱼在它的下方,所以插鱼时,只有瞄准看到的鱼的下方才能插到鱼。

泥土烫,海水凉,是和物体的比热容有关,水的比热容比土的比热容大,在同样的日照条件下,吸收相同的热量,水的温度变化小,土的温度变化大,所以水凉,土烫;

用船桨划水时,动力臂小于阻力臂,所以船桨属于费力杠杆,费力但省距离;

用船桨向后划水时,船桨给水一个向后的力,由于物体间力的作用是相互的,所以水也给船桨一个向前的力,这个力就是船前进的动力.

因为光的折射定律,当从上面看水中的物体时,会感到物体的位置比实际位置高一些,并且物体的光线进入观察者的眼睛,当渔民看水中的鱼时,正是应了这一现象,看到的鱼的位置并不是真正的鱼的位置,而是鱼得虚像;因此在叉鱼时,只有瞄准鱼的下方才能把鱼叉到.

单项选择题

Passage One

The world is going through the biggest wave of mergers and acquisitions ever witnessed. The process sweeps from hyperactive America to Europe and reaches the emerging countries with unsurpassed might. Many in these countries are looking at this process and worrying: "Won’t the wave of business concentration turn into an uncontrollable anti-competitive force"

There’s no question that the big are getting bigger and more powerful. Multinational corporations accounted for less than 20% of international trade in 1982. Today the figure is more than 25% and growing rapidly. International affiliates account for a fast-growing segment of production in economies that open up and welcome foreign investment. In Argentina, for instance, after the reforms of the early 1990s, multinationals went from 43% to almost 70% of the industrial production of the 200 largest firms. This phenomenon has created serious concerns over the role of smaller economic firms, of national businessmen and over the ultimate stability, of the world economy.

I believe that the most important forces behind the massive M&A wave are the same that underlie the globalization process: falling transportation, and communication costs, lower trade and investment barriers and enlarged markets that require enlarged operations capable, of meeting customers’ demands. All these are beneficial, not detrimental to consumers. As productivity grows, the world’s wealth increases.

Examples of benefits or costs of the current concentration wave are scanty. Yet it is hard to imagine that the merge of a few oil firms today could recreate the same threats to competition that were feared nearly a century ago in the U.S., when the Standard Oil trust was broken up. The mergers of telecom companies, such as World Corn, hardly seem to bring higher prices for consumers or a reduction in the pace of technical progress. On the contrary, the price of communications is coming down fast. In cars, too, concentration is increasing—witness Daimler and Chrysler, Renault and Nissan—but it does not appear that consumers am being hurt.

Yet the fact remains that the merger movement must be watched. A few weeks ago, Alan Greenspan warned against the megamergers in the banking industry. Who is going to supervise, regulate and operate, as lender of last resort with the gigantic banks that are being created Won’t multinationals shift production from one place to another when a nation gets too strict about infringements to fair corn petition And should one country take upon itself the role of "defending competition" on issues that affect many other nations, as in the U. S..

From Paragraph 4 we can infer that ().

A.the increasing concentration is certain to hurt consumers

B.World Corn serves as a good example of both benefits and costs

C.the costs of the globalization process are enormous

D.the Standard Oil trust might have threatened competition

阅读理解与欣赏

课内文言文阅读。(15分)

沛公旦日从百余骑来见项王,至鸿门,谢曰:“臣与 * * 戮力而攻秦, * * 战河北,臣战河南,然不自意能先入关破秦,得复见 * * 于此。今者有小人之言,令 * * 与臣有郤。”项王曰:“此沛公左司马曹无伤言之。不然,籍何以至此?”项王即日因留沛公与饮。项王、项伯东向坐;亚父南向坐——亚父者,范增也;沛公北向坐;张良西向侍。范增数目项王,举所佩玉玦以示之者三,项王默然不应。范增起,出召项庄,谓曰:“君王为人不忍,若入前为寿,寿毕,请以剑舞,因击沛公于坐,杀之。不者,若属皆且为所虏。”庄则入为寿。寿毕,曰:“君王与沛公饮,军中无以为乐,请以剑舞。”项王曰:“诺。”项庄拔剑起舞,项伯亦拔剑起舞,常以身翼蔽沛公,庄不得击。

小题1:解释下列加点字。(6分)

(1)至鸿门,曰(   )          (2) * * 战北,臣战河南(    )

(3)沛然不自能先入关破秦公(  )(4)不,籍何以至此(  ) 

(5)张良西向(    )          (6)常以身蔽沛公(  )

小题2:下列句子中与“常以身翼蔽沛公”的“以”字意义和用法不同的一项是(3分)

A.请以剑舞

B.乃欲以生劫之

C.使工以药淬之

D.阙秦以利晋小题3:下列对文段有关内容的分析和概括,不正确的一项是(    )(3分)

A.这一段写了一系列的事件:刘邦谢罪、项羽设宴、范增举玦、项羽不应、项庄舞剑、项伯护刘等,这些事写得张弛有度,波澜起伏,惊心动魄,扣人心弦。

B.到鸿门后,刘邦先称臣谢罪,把欲王关中的野心否认得干干净净,接着把项羽要“击破”他的事,转到“小人之言”上去,从而得到了项羽的好感。

C.项羽听了刘邦的话后,立即把自己所得情报的来源说了出来,还设宴招待刘邦,可见他是个心地善良,勇于改过的人。

D.范增见项羽“默然不应”,怕失去时机,乃叫项庄以舞剑为由,趁机刺杀刘邦,足见他是个心狠手辣,为达目的不择手段的人。小题4:把下列句子译成现代汉语。(3分)

范增数目项王,举所佩玉玦以示之者三,项王默然不应。