第4部分，阅读理解

　　第一篇　The Northern Lights

　　The sun is stormy and has it own kind ofweather. It is so hot and active that even the Sun’sgravity cannot hold its atmosphere in check! Energy flows away from the Suntoward the Earth in a stream of electrified particles that move at speedsaround a million miles per hour. These particles are called plasma, and thestream of plasma coming from the Sun is called the solar wind. The more activethe Sun, the stronger the solar wind.

　　The solar wind constantly streams toward theEarth, but don’t worry because a protective magneticfields surrounds our planet. The same magnetic field that makes your compasspoint north also steers the particles from the Sun to the north and southpoles. The charged particles become trapped in magnetic belts around the Earth.When a large blast of solar wind crashes into the Earth’s magnetic field first gets squeezed and then the magnetic fieldlines break and reconnect.

　　The breaking and reconnecting of the magneticfield lines can cause atomic particles called electrons trapped in the belts tofall into the Earth’s atmosphere at the poles. As theelectrons fall into the Earth, they collide with gas molecules in theatmosphere, creating flashes of light in the sky.

　　Each atmospheric gas glows a different color.Oxygen and nitrogen glows red and green and nitrogen glows violet-purple. Asthese various colors glow and dance in the night sky, they create the NorthernLights and the Southern Lights.

　　Watching auroras(北极光)is fun and exciting, but normally you can only see them in places far northlike Alaska and Canada. The movement of the aurora across the sky is usuallyslow enough to easily follow with your eyes but they can also pulsate(跳动), flicker(闪烁), or even move like waves.During solar maximum, 5 auroras are seen as far south as Florida, even Mexico!Aurorasoften seem to be very close to the ground, but the lowest aurora is still about100 kilometers above the ground, a distance much higher than clouds are formedor airplanes can fly. A typical aurora band can be thousands of kilometerslong, a few hundred kilometers high, but only a few hundred meters thick.

　　We hope you are able to travel to far-northplaces like the Arctic Circle and see the Northern Lights at least once duringyour lifetime. We know you will never forget it!

　　31. The solar wind comes into being as aresult of______

　　A. disappearance of the Sun’s gravity.

　　B. unpredictable weather of the Sun.

　　C. fast flow of energy away from the Sun.

　　D. a stream of particles being blown away.

　　32. What happens when solar wind comes to theEarth?

　　A. A protective magnetic field is formed atthe same time.

　　B. It is trapped in magnetic belts around theEarth.

　　C. It destroys the protective magnetic fieldsurrounding the Earth.

　　D. It breaks magnetic field lines and doessevere damage to the ???

　　33. The Northern Lights are createdwhen______

　　A. atomic particles fall to the Earth and collidewith atmospheric gases.

　　B. the magnetic field lines fail toreconnect.

　　C. the electrons falling to the Earth shinein different colors.

　　D. oxygen and nitrogen are separated from theatmospheric gases.

　　34. Which of the following statements is trueof the Northern Lights?

　　A. Their movement is slow enough to be observedwith the eyes.

　　B. People cannot see them unless traveling toAlaska or Canada

　　C. They are very close to the ground.

　　D. They are very long and thick.

　　35. What is the author’s tone toward the Northern Lights?

　　A. Indifferent

　　B. Sarcastic

　　C. Sharp

　　D. Appreciative