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Directions:
The following paragraphs are given in a wrong order. For Questions 41-45, you are required t reorganize these paragraphs into a coherent article by choosing from the list A-E to fill in each numbered box. The first and the last paragraphs have been placed for you in Boxes. Mark your answers on ANSWER SHEET 1. (10 points)
[A] Astronomers are interested in comets because they are simpler and more primitive than planets. Both types of body formed 4.5 billion years ago from a cloud of gas and dust around the young sun. Comets, though, are believed to have changed little from those days while planets, being larger and thus more prone to heating up and melting (the heat is generated by radioactive minerals, and trapped inside large bodies), have undergone significant alteration. A comet is therefore something of a cosmic time capsule.
By observing how the crater forms, and the shape of the debris cloud, NASA's scientists hope to be able to tell something about the rigidity of the comet's material and how porous it is. And by analysing the spectrum of light from the debris, they will find out that material's chemical composition-although the comet has been giving up some of these secrets unprompted, with a series of natural outbursts in recent weeks.
[C] Deep Impact itself is a actually composed of two smaller vehicles-a mother ship that will fly past the comet taking photographs and conducting other measurements, and a sophisticated, steerable copper bullet weighing 372kg that is intended to smash into the comet.
[D] Deep Impact's scientists, though, are not just trying to create an expensive display of patriotic pyrotechnics. By observing what is ejected from the crater created when part of the probe hits the comet they also hope to catch a glimpse of the material from which the Earth and the other planets were formed.
[E] Amateur observers in the western United States should be able to see Tempel 1 light up during the impact through a small telescope or possibly even a large pair of binoculars. For more information, consult http://deepimpact. umd.edu/amateur.
[F] America's space agency, NASA, has always had one eye on the crowd. It is not, therefore, a coincidence that its Deep Impact probe will arrive at its target, comet, Tempel 1, on July 4th. As is traditional, the anniversary of the American rebellion will be celebrated by fireworks on Earth. This year, thanks to the cunning of the agency's interplanetary navigators, there should be fireworks in the heavens, too.
[G] On July 3rd, the bullet will separated from the mother ship and begin its journey towards Tempel 1. At around 05:52 Universal Time the next day it should hit the comet.
Order
F 41. 42 43 44 45 E
Answer D A C G B
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发表于 2016-8-9 08:15:55