2014年4月托福考试模拟试卷及答案(第四套)_第8页

　　The temperature of the Sun is over 5,000 degrees Fahrenheit at the surface, but it rise 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.

　　(5) However, no one really knows, since the center of the Sun can never be directly observed.

　　Solar astronomers do know that the Sun is divided into five layers or zones. Starting at

　　the outside and going down into the Sun, the zones are the corona, chromosphere, photo-

　　sphere, 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

　　(10) ends and the main body of the Sun begins.

　　The Sun's outermost layer begins about 10,000 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

　　(15) Sun's rays.

　　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 spikelike rays near the Sun's north and south poles. The corona

　　is thickest at the Sun's equator.

　　(20) 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 planets. By the time the Sun's corona rays reach the

　　Earth, they are weak and invisible.

　　Where in the passage does the author compare the light of the Sun's outermost layer to that of another astronomical body?

　　(A) Lines 2-3

　　(B) Lines 9-10

　　(C) Lines 16

　　(D) Lines 22-23

　　All of the following are parts of the Sun's atmosphere EXCEPT the

　　(A) corona

　　(B) chromosphere

　　(C) photosphere

　　(D) core