問題詳情

IV. Reading Comprehension: Choose the best answer to each question.46-50    Auroras, often called Northern Lights (Aurora Borealis) and Southern Lights (Aurora Australis), arespectacular light displays (from the Latin word aurora, “sunrise” or the Roman goddess of dawn)predominantly seen in the high latitude (Arctic and Antarctic) regions. Auroras occur because ofinteractions between Earth’s magnetic field and solar winds. The solar wind is a stream of chargedparticles emitted from the sun’s corona that travels far into space at speeds of up to 400 miles per second.Charged particles within the solar winds collide with atmospheric atoms and molecules when they reachEarth’s magnetic field. The collisions cause quantum leaps, which mean the kinetic energy within theelectrons of the particles are converted to light. The collisions of different particles result in differentcolored lights. Atomic oxygen produces red and green lights, nitrogen produces pink, blue, or violet light,helium produces purple lights and neon produces rippled orange light. Auroras come in a vast array ofshapes and forms such as arcs, swirls, “curtains” and glowing shapes. They often appear to be moving.   Auroras often occur as a result of a geomagnetic storm. A geomagnetic storm is the temporarydisturbance of the Earth’s magnetic field as a result of an event in space such as a solar flare or coronalmass ejection (the ejection of charged particles from the sun’s corona). In noteworthy geomagneticstorms, Auroras can be seen well south (or north) of where they usually occur. The famous GreatGeomagnetic Storms of 1859 produced what witnesses call the most spectacular auroras ever seen. Suchauroras were seen throughout the United States, Japan, and Australia. The event lasted for almost a week.
46. Which of the following is a necessary element for an aurora?
(A) a stream of polar wind
(B) solar collision with charged particles
(C) the conversion of kinetic energy
(D) the far-travelling corona of the sun

參考答案

答案：C
難度：適中0.5
統計：A(0),B(0),C(0),D(0),E(0)

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