2014理工类职称英语考前自测练习完形填空4

　　What Is the Coolest Gas in the Universe?

　　What is the coldest air temperature ever recorded on the Earth? Where was this low temperature recorded? The coldest recorded temperature on Earth was -91℃，which (51)in Antarctica in1983.

　　We encounter an interesting situation when we discuss temperatures in (52).Temperatures in Earth orbit actually range from about +120℃ to -120℃.The temperature depends upon (53)you are in direct sunlight or shade.Obviously，-120℃ is colder than our body can safely endure.Thank NASA science for well-designed space (54)that protect astronauts from these temperature extremes.

　　The space temperatures just discussed affect only our area of the solar (55).Obviously, it is hotter closer to the Sun and colder as we travel away from the Sun.Astronomers estimate temperatures at Pluto are about -210℃.How cold is the lowest estimated temperature in the entire universe? Again，it depends upon your (56).We are taught it is supposedly (57)to have a temperature below absolute zero，which is -273℃, at which atoms do not move.Two scientists，whose names are Comell and Wieman，have successfully cooled down a gas to a temperature barely (58)absolute zero.They won a Nobel Prize in Physics in 2001 for their work ― not a discovery，in this case.

　　Why is the two scientists’ work so important to science?

　　In the 1920s，Satyendra Nath Bose was studying an interesting (59)about special light particles we now call photons.Bose had trouble (60)other scientists to believe his theory， (61)he contacted Albert Einstein.Einstein’s calculations helped him theorize that atoms (62)behave as Bose thought ― but only at very cold temperatures.

　　Scientists have also discovered that (63) atoms can help them make the world’s atomic clocks even more accurate.These clocks are so accurate today they would only lose one second (64)six million years! Such accuracy will help us travel in space because distance is velocity times time(d=v×t).Withthe long distances involved in space (65), we need to know time as accurately as possible to get accurate distance.

　　51.A.opened B.occurred C.opposed D.operated

　　52.A.Earth B.space C.planet D.star

　　53.A.whether B.where C.what D.when

　　54.A.foods B.beds C.tools D.suits

　　55.A.wind B.energy C.system D.rays

　　56.A.education B.status C.knowledge D.location

　　57.A.reasonable B.wonderful C.impossible D.necessary

　　58.A.above B.below C.within D.beyond

　　59.A.invention B.theory C.paper D.experiment

　　60.A.convincing B.begging C.ordering D.forcing

　　61.A.and B.though C.but D.so

　　62.A.will B.would C.must D.can

　　63.A.ultra-small B.ultra-fast C.ultra-hot D.ultra-cold

　　64.A.any B.each C.every D.some

　　65.A.travel B.research C.walk D.station

　　答案：BBADC DCABA DBDCA

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