职称英语考试

试题来源：职称英语模拟题-理工类-阅读理解

Snowflakes

You've probably heard that notwo snowflakes are alike.Of course,nobody has ever confirmed that statement byexamining every one of the estimated one septillion snowflakes that drift toEarth each year.still,Kenneth Libbrecht,a professor at the California Instituteof Technology,is confident that the statement is true.

Snowflakes aren't flaky,saysLibbrecht.At their basic level,they're crystalline.The lattice of everysnowflake is six-sided in shape.The simplest snow crystals are six-sided flatplates and six-sided columns.Such crystals are common in places where the airis extremely cold and dry.Snow crystals acquire their special beauty when theirsimple six-sided symmetry blossoms.Under the right conditions,each of the sixcorners of a crystal sprouts what is called an arm.In a matter of minutes,thearms can become highly ornate and give the crystal a star like appearance.

Several factors in theenvironment affect the shape and growth rate of a snow crystal.One factor ishumidity.Crystals grow faster and in more intricate shape as humidityincreases.A second factor is air temperature.A snowflake is born when severalmolecules of water vapor in a could land on a speck of dust and freeze to forma simple crystal.As the young crystal bops around in the cloud,it passesthrough air pockets of varying temperatures.If the crystal passes through apocket of air that is,says,—15 degrees Celsius,it will grow quickly and sprout six arms,saysLibbrecht.If the crystal is then tossed into a warmer pocket,one about-10℃,the arms' tips will stop growing quickly and form six-sideplates.If the crystal then drifts into an even warmer pocket of about -℃,its top and bottom will grow more quickly than its sides and becomemore column like in shape.

In the course of its life span,asnow-crystal might flutter through many warmer and colder pockets,acquiring acomplicated and unique growth history.Such a history will give rise to asnowflake that is unlike any other.Each arm on the snowflake will look exactlylike every other one,but the crystal itself will be one of a kind.

Using his coolingtanks,Libbrecht has learned how to create snow crystals of different shapes—plates,colhuns,needlesetc.Libbrecht has even refined his techniques so that he can make crystals thatlook highly similar to one another.Still,he lacks the control to manufactureidentical twin snowflakes.A slight difference in humidity and temperature canupset the growth profile of a crystal.

1.What does Professor Libbrechtbelieve to be true?

A.No two snowflakes are exactlythe same in shape.

B.Somebody has examined all thesnowflakes that on Earth.

C.The statement that no twosnowflakes are alike is confirmed.

D.None of the above.

2.What do the simplest snowcrystals look like?

A.They have six columns.

B.They are flaky.

C.They are cubic in shape.

D.They are six-sided.

3.What are the factors thataffect the shape and growth rate of a snow crystal?

A.Humidity and temperature.

B.Water and falling speed.

C.Air and altitude.

D.Both B and C.

4.It can be felt from the descriptionin the 2nd paragraph that the author

A.admires the beauty of thesnowflakes.

B.dislikes the changing growthhistory of the snowflakes.

C.has a particular feeling forthose flower-like crystals.

D.likes to compare snowflakesto the stars in the sky.

5.Libbrecht is not able to

A.create snow crystals ofdifferent shapes.

B.make crystals that looksimilar to one another.

C.create snowflakes that areexactly alike.

D.refine his techniques.

试题出处：http://www.examtiku.com/shiti/1679524794.html
网考网参考答案：A、D、A、A、C
网考网解析：进入考试题库查看解析
大数据分析：根据网考网与考试题库的统计，该试题：
12%的考友选择了A选项
66%的考友选择了B选项
17%的考友选择了C选项
5%的考友选择了D选项
考友解析与评论：
 · 这个答案应该是错误的
 · 不注意就选错了,其实这条是会的.坑人的题目.
 · 原先有道题和这题几乎一样，只是稍有不同，大家看看就可理解了，那个答案正确。