问题 单项选择题

甲类传染病在某县暴发时,如果对疫区实施封锁,必须经()

A.省卫生厅决定

B.市级卫生行政部门决定

C.省级人民政府决定

D.市级人民政府决定

E.县级人民政府决定

答案

参考答案:B

阅读理解与欣赏

阅读下面的文字,完成19-21小题。

太空天梯可能实现的理由 

1979年,美国作家亚瑟·克拉克在一本名为《天堂的喷泉》的科幻小说中写道:“根据天体力学的定律,如果某个物体在天空中静止不动,就可以从其上向地面垂放下缆绳,通过这种方式,就能够把地球和宇宙空间联结起来。” 

1960年,前苏联科学家阿斯塔诺夫就公开发表了修建太空天梯(又称“宇宙电梯” )的构想。不过,正如克拉克在书中表达的对于登天梯或通天柱的看法那样,“尽管从理论上不能说有什么错误,但实际上却很难找到实现的方法。”那么,修建太空天梯究竟会碰到什么样的实际困难呢? 

大家知道,人造卫星在围绕地球进行旋转运动时,会产生离心力。其离心力刚好与地球对卫星的吸引力(万有引力)互相平衡,才会使得卫星作圆周运动并围绕地球进行旋转。如果地球引力过强,人造卫星就会掉落到地面,反之,如果离心力过强,就会使得人造卫星远离地球而去。 

根据牛顿的万有引力定律,卫星所受地球(万有)引力的强弱与其到地球(中心)距离的平方成反比,当卫星在地球引力比较弱的高轨道围绕地球不断旋转时,其离心力也会相应地变小。同时,卫星的速度与离心力成正比,所以卫星的运转速度就变慢了。 

实际上,处于地球上空高度约400公里处的国际空间站,围绕地球转一圈,大约只需要90分钟左右。而处于赤道上空高度为35786公里轨道上面运行的气象观测卫星,围绕地球旋转一圈,大约需要24小时左右,因此,它的旋转周期与地球与自转周期相同。这就意味着对于24小时绕地球一周的人造卫星而言,卫星的“正下方”始终会对着地球表面的同一个场所。反之,如果从卫星“正下方”地面的某处向天空中看去,卫星也好像静止不动,始终处于天顶上面的同样位置。 

所以,就将这样处于地球同步轨道运行着的卫星称为“静止卫星” ,并把静止卫星运行的轨道称为“静止轨道”。 

如前文所述,静止卫星正是对于某个区域,在天空中静止不动的物体。从这样的地球同步静止卫星上向地面垂放下缆绳,随着缆绳的加长延伸(假如忽略风力等因素的影响),缆绳的前端就会逐渐到达地面的同步观察点。那么,就可以沿着这些缆绳进行升降,操作往返于地面与卫星之间运送人员和货物了。

这正是“太空天梯”天才构想的发端。但只是简单地从静止卫星上施放缆绳,要想达到地面,是远远不够的。由于缆绳本身也有重量,就会使静止卫星的重心产生偏移,从而使其掉落到地面上。 

为了防止发生类似现象,必须要沿着地球的相反方向也施放出同样长度的缆绳,以便保持施放卫星的重心位置不会发生改变。为此,在必要时,还需要在施放卫星或轨道站平台的上方缆绳的顶端安装重物,以帮助缆绳系统保持平衡。 

太空天梯的操作原理与一般建筑物所使用的普通电梯是完全不同的。普通电梯是通过楼层顶端的滑车卷绕钢缆,使电梯箱体进行升降的,而且在钢缆的两端还安装着一些铁块用于电梯系统的平衡配重。而太空天梯的升降机本身是带有动力的,它会依靠自身的动力沿着缆绳在天空中或上升或下降,在地面站和各级太空轨道站之间往返运输货物和人员。 

太空天梯主要组成部件有,处于静止轨道上面的“静止轨道空间站”,延伸在数公里的天空中,联结着各级轨道空间站的太空缆绳系统,沿着缆绳系统上下来回运行的具有自主动力控制的升降机系统。此外,在地球表面赤道附近的海岛或海洋平台上,还需要建设可以供太空升降机起落装卸货物、上下人员以及维修使用的大型地面基地设施。

(选自 《科学世界》2010年第4期 《太空天梯:从科幻到现实》) 

小题1:作为科普文章,开头引述 《天堂的喷泉》这部科幻小说的目的是什么?(4分) 

小题2:太空天梯与普通电梯有什么不同?请概括其中最本质的区别并简要说明。(5分) 

小题3:综观全文,你认为当前建造太空天梯最难又最关键的是哪一步?简要说说理由。                                                  (6分)

阅读理解

第三部分:阅读理解(共2节,满分35分)

第一节:阅读下列短文,从每题所给的四个选项(A、B、C和D)中,选出最佳选项,并在答题卡上将该项涂黑(共15小题,每小题2分,满分30分).

ARGENTINA’S new government faced public anger over its recent decision to greatly reduce the dollar value of its citizens’ bank savings. More than two-thirds of Argentine bank savings were in US dollars. The country’s recession (衰退),which is in its fourth year, has left a third of Argentine’s 36 million people in poverty.

A few angry people took the streets on January 21, beating pots and pans in protest. And a group of unemployed Argentines demanding jobs blocked a major highway into Argentina’s capital city, Buenos Aires.

Argentines fear they could lose up to half the dollar value of their savings. Some on the street said the country’s fifth president in the past month has already failed them.

After three weeks in power, President Eduardo Duhalde has broken his first and biggest promise. He said he would return people’s savings in the currency in which were deposited(开户). Duhalde aims to make exports more competitive. But this is expected to have a serious effect on ordinary families, for the simple reason that in Argentine, 80 percent of loans and mortgages(抵押) are in dollars. The government froze all the bank savings made in dollars, worth US$45 billion in total to stop a run on banks. This cause huge street protest earlier this month and contributed to the downfall of two governments. “Most of my life savings were just taken away from me, “ said Jose, a 38-year-old citizen. “I was going to move to Italy but now I can’t because my money is trapped here. Argentina is like a prison.”

The government loosened the new banking rules a little bit on January 17. However, people still don’t have free access to their bank account. They are only allowed to take out rapidly devaluing pesos, even though their savings are in US dollars.

The banking controls will remain in place for about three months, with a few exceptions for the elderly or people with sever illnesses who need crash.

56. How many people have been left in poverty because of Argentina’s economic recession?

A. all Argentines people                             B. 24 million people

C. 12 million people                                 D. 36 million people

57. What cause Argentines to protest in the streets earlier this month?

Argentina’s economic recession.

Argentina’s new government made its people angry.

Argentina’s government froze all the bank savings made in US dollars.

Two of Argentina’s governments failed to make exports more competitive.

58. What does the sentence… my money is trapped here” mean_____?

My bank savings have been frozen by the government.

I don’t want to take my money away.

I don’t have any money in the bank.

My money has been taken by the Italian government.

59. According to the article, which of the following sentences is correct?

people can get their money from the bank freely.

People are only allowed to get US dollars from the bank.

The government will only allow people to get pesos from the bank.

The banking controls will loosen a little in three months’ time.

60. Argentines cannot get US dollars from the bank unless they are_____.

A. ordinary people                             B. rich or government officials

C. poor people                                          D. old or seriously ill