问题 问答题 论述题

谈谈大陆漂移说的基本观点和主要根据

答案

参考答案:

(1)基本观点

1912年德国学者魏格纳提出了大陆漂移说,他认为:在大约3亿年前的石炭纪后期,地球上所有的大陆曾经联结在一起,构成一个统一的大陆(称为泛大陆),围绕它的是一片广阔的海洋(称为泛大洋),后来由于受地球自转离心力和潮汐力的作用,从中生代开始,泛大陆逐渐破裂、分离,由硅铝层组成的较轻的陆壳浮在较重的硅镁层洋壳之上漂移〔就像冰山漂浮在水面上一样〕,直至形成现代的海陆分布轮廓。大西洋、印度洋、北冰洋是在大陆漂移过程中形成的,太平洋则是泛大洋的残余。

(2)主要根据

大陆漂移说主要是根据大西洋两岸大陆轮廓、地层、地质构造、古生物、古气候等方面的相似性和连续性而提出的。如:

1)南美洲和非洲两大陆相对着的海岸线惊人地相似,完全可拼合在一起,非洲南部的开普山脉可与南美的布宜诺斯艾利斯山脉连接;

2)北美与西北欧的加里东褶皱带和海西褶皱带完全可沿走向相接;

3)从古气候、古生物群分布看,南美、非洲、印度、澳大利亚在古生代时期很相似,而中生代以后则有显著不同。

4)50年代以来,由于古地磁及海洋地质等方面的研究,提供了许多新的论据,使一度沉寂的大陆漂移说重新复活和得到发展。

上述都说明大陆曾联结—起,以后才逐渐分离。

阅读理解

There are little cars that may some day take the place of today’s automobiles(汽车). If everyone drives such a little car in the future, there will be less pollution in the air, there will be more parking space in cities, and the streets will be less crowded. The space now for one car of the usual size can hold at least three such little cars.

The little cars will cost much less to own and to drive. Driving will be safer, too, as these little cars can go only 65 kilometers an hour.

The cars of the future will be fine for going around the city, but they will not be useful for going far away. If the car is powered by electricity, it will have two batteries—one battery for the motor and the other for the horn (喇叭), signals (信号灯), etc. Little cars which are powered by gas will go 45 kilometers before needing to stop for more gas.

If big cars are still used along with the small ones, two sets of roads will be needed to set up in the future. Some roads will be used for the big, fast cars, and other roads will be needed for the small, slower ones.

1. What’s the advantage (优势) of the small cars?

A. There won’t be so much pollution and the small cars won’t be so expensive as the big ones.

B. It will be safer to drive these small cars.

C. There will be more space for cars to park.

D. All of the above.

2. Two sets of roads are necessary in the future in order to      .

A. prevent car accidents

B. make the city more beautiful

C. let small cars run fast

D. limit the speed of the cars

3. Which of the following is true according to the passage?

A. A car of the usual size now is three times as big as the small car.

B. The small car with a speed of 65 kilometers an hour is much more useless than a car of the usual size.

C. the little car will be safer but cost more.

D. The little car will need more gas.

4. The best title for this passage should be      .

A. Big Cars and Small Cars

B. How to Drive Small Cars

C. Cars for Tomorrow

D. Cars for Everyone

单项选择题