学位英语

Structure of the Sun

1 The temperature of the Sun is over 5,000 degrees Fahrenheit at the surface, but it rises to perhaps more than 16 million degrees at the center. The Sun is so much hotter than the Earth that matter can exist only as a gas, except at the core. In the core of the Sun, the pressures are so great against the gases that, despite the high temperature, there may be a small solid core. However, no one really knows, since the center of the Sun can never be directly observed.

2 Solar astronomers do know that the Sun is divided into five layers of zones. Starting at the outside and going down into the sun, the zones are the corona, chromosphere, photosphere, convection zone, and finally the core. The first three zones are regarded as the Sun's atmosphere. But since the Sun has no solid surface, it is hard to tell where the atmosphere ends and the main body of the Sun begins.

3 The Sun’s outermost layer begins about l0000 miles above the visible surface and goes outward for millions of miles. This is the only part of the Sun that can be seen during an eclipse such as the one in February 1979. At any other time, the corona can be seen only when special instruments are used on cameras and telescopes to shut out the glare of the Sun's rays.

4 The corona is a brilliant, pearly white, filmy light, about as bright as the full Moon. Its beautiful rays are a sensational sight during an eclipse. The corona’s rays flash out in a brilliant fan that has wispy spider-like rays near the Sun's north and south poles. The corona is thickest at the Sun's equator.

5 The corona rays are made up of gases streaming outward at tremendous speeds and reaching a temperature of more than 2 million degrees Fahrenheit. The rays of gas thin out as they reach the space around the planet. By the time the Sun's corona rays reach the Earth, they are weak and invisible.

23Paragraph 2

24Paragraph 3

25Paragraph 4

26Paragraph 5

A.Basic description of the core

B. Characteristics of the corona

C. The composition of the corona rays

D. Five layers of zones of the sun

E. Characteristics of the corona rays

F. The eclipse in February 1979

正确答案:DBEC

解析:23.第二段介绍了太阳的五层结构。

24.第三段介绍了太阳的最外层日冕层的特点。

25.第四段介绍了日冕层射线的特点。

26.第五段介绍了日冕层射线的组成。

27Matter on the Sun can exist only in the form of a gas because .

28The Sun’s atmosphere includes .

29During the eclipse in February 1979, the corona is that can be seen.

30When the Sun's corona rays reach the Earth, they become .

A.strong and visible

B. chromosphere, photosphere, convection zone

C. the corona, chromosphere, photosphere

D. of the high temperature

E. weak and invisible

F. the only part of the Sun

正确答案:DCFE

解析:27.问题问的是：为什么太阳周围物质只能以气体形态出现?根据第一段第二句可知原因是太阳内部温度太高。

28.问题问的是：太阳的大气层包括什么?根据第二段第二句和第三句可知C为正确选项。

29.问题问的是：日食出现是，日冕层是太阳唯一可以被人们观看到的部分。根据第三段第二句，可知F 为正确选项。

30.问题问的是：当日冕层射线到达地球时，射线会变成什么样?根据最后一句可知E为正确答案，即射线会变得很微弱，人们几乎看不到。

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