2021年北师大大学考博英语真题试卷.pdf

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1、2 0 2 1年 北 师 大 大 学 考 博 英 语 真 题 试 卷 2021年 北 京 师 范 大 学 考 博 英 语 真 题 试 卷（总 分 68,做 题 时 间 9 0 分 钟）1.Reading ComprehensionThe human ear contains the organ for hearing and the organ for balance.Both organs involve fluid-filled channels containing hair cells that produceelectrochemical impulses when the hair

2、s are stimulated by moving fluid.Theear can be divided into three regions:outer,middle,and inner.The outer earcollects sound waves and directs them to the eardrum separating the outer earfrom the middle ear.The middle ear conducts sound vibrations through threesmall bones to the inner ear.The inner

3、ear is a network of channelscontaining fluid that moves in response to sound or movement.To performthe function of hearing,the ear converts the energy of pressure waves movingthrough the air into nerve impulses that me brain perceives as sound.Vibrating objects,such as the vocal cords of a speaking

4、person,create wavesin me surrounding air.These waves cause the eardrum to vibrate with the samefrequency.The three bones of the middle ear amplify and transmit thevibrations to the oval window,a membrane on the surface of the cochlea,theorgan of hearing.Vibrations of me oval window produce pressure

5、waves in thefluid inside me cochlea.Hair cells in the cochlea convert the energy of thevibrating fluid into impulses that travel along the auditory nerve to thebrain.The organ for balance is also located in the inner ear.Sensationsrelated to body position are generated much like sensations of sound.

6、Haircells in the inner ear respond to changes in head position with respect togravity and movement.Gravity is always pulling down on the hairs,sending aconstant series of impulses to the brain.When the position of the headchanges-as when the head bends forward the force on the hair cells changesits

7、output of nerve impulses.The brain then interprets these changes todetermine the heads new position.1.What can be inferred about the organs for hearing and balance?A Bothorgans evolved in humans at the same time.B Both organs send nerve impulsesto the brain.C Both organs contain the same amount of f

8、luid.D Both organs are located in m e e a rs middle region.2.Hearing involves a ll of the following E X C E P T.A motion of the vocalcords so that they vibrate B stim ulation of hair c ells in flu id-fille dchannels C am plification of sound vibrationsD conversion of wave energy into nerve impulses

9、3.I t can be inferred from Paragraphs 2 and 3 that the cochlea is a parto f.A the outer ear B m e eardrum C the middle ear D the inner ear 4.What can be inferred from Paragraph 4 about gravity?A Gravity has anessential role in the sense of balance.B The ear converts gravity into soundwaves in the ai

10、r.C Gravity is a force that originates in the human ear.D Theorgan for hearing is not subject to gravity.5.In th is passage,the author mainly e x p l a i n s.A the organs of thehuman ear B the function of the hearing C the three regions of the earD how the ear organ performs the hearing and balanceT

11、he geology of the Earth，s surface is dominated by the p articu larproperties of water.Present on Earth in solid,liquid,and gaseous states,water is exceptionally reactive.It dissolves,transports,and precipitatesmany chemical compounds and is constantly modifying the face of the Earth.Evaporated from

12、the oceans,water vapor forms clouds,some of which aretransported by wind over the continents.Condensation from the clouds providesthe essential agent of continental erosion:rain.Precipitated onto the ground,the water tric k le s down to form brooks,streams,and rivers,constituting whatis called the h

13、ydrographic network.This immense polarized network channelsthe water toward a single receptacle:an ocean.Gravity dominates th is entirestep in the cycle because water tends to minimize its potential energy byrunning from high a ltitu d es toward the reference point that is sea level.The rate at whic

14、h a molecule of water passes through the cycle is not randombut is a measure of the re la tiv e size of the various reservoirs.If w e defineresidence time as the average time for a water molecule to pass through one ofthe three reserv o irsatmosphere,continent,and ocean-we see that the timesare very

15、 different.A water molecule stays,on an average,eleven days in theatmosphere,one hundred years on a continent and forty thousand years in theocean.This la st figure shows the importance of the ocean as the principalreservoir of the hydrosphere but also the rapidityof water transport on the continent

16、s.A vast chemical separationprocess takes places during the flow of water over the continents.Solubleions such as calcium,sodium,potassium,and some magnesium are dissolved andtransported.Insoluble ions such as aluminum,iron,and silico n stay wherethey are and form the thin,fe r tile skin of soil on

17、which vegetation can grow.Sometimes so ils are destroyed and transported mechanically during flooding.The erosion of the continents thus re su lts from two closely linked andinterdependent processes,chemical erosion andmechanical erosion.Their respective interactions and efficiency depend ondifferen

18、t factors.6.According to the passage,clouds are prim arily formed by w a t e r.Ap recipitating onto the groundB changing from a solid to a liquid state C evaporating from the oceans Dbeing carried by wind 7.The passage suggests that the purpose of the t o.A determine the size of molecules of water B

19、 prevent soil erosion causedby floodingC move water from the Earthy s surface to the oceansD regulate the rate of water flow from streams and rivers 8.What determines the rate at which a molecule of water moves through thecycle,as discussed in the third paragraph?A The potential energy containedin w

20、ater.B The effects of atmospheric pressure on chemical compounds.C The amountsof ra in fa ll that fa ll on the continents.D The re la tiv e size of the waterstorage areas.9.All of the following are examples of soluble ions E X C E P T.Amagnesium B ironC potassium D calcium 10.The word A relationship

21、 B growth C influence D effectivenessScientists have long understood that supermassive black holes weighingmillions or billions of suns can tear apart stars that com e too close.Theblack hotels gravity pulls harder on the nearest part of the star,animbalance that pulls the star apart over a period o

22、f minutes or hours,once itgets close enough.Scientists say this uneven pulling is not the onlyhazard facing the star.The strain of these unbalanced forces can also triggera nuclear explosion powerful enough to destroy the star from within.MatthieuBrassart and Jean-Pierre Luminet of the Observatoire

23、de Paris in M eudon,France,carried out computer simulations of the final mom ents of such anunfortunate sta rs life,as it veered towards a supermassive black hole.W h en the star gets close enough,the uneven forces flatten it into a pancakeshape.S om e previous studies had suggested this flattening

24、would increase thedensity and temperature inside the star enough to trigger intense nuclearreactions that would tear it apart.But other studies had suggested that thepicture would be complicated by shock waves generated during the flatteningprocess and that no nuclear explosion should occur.The new

25、simulationsinvestigated the effects of shock waves in detail,and found that evenw hen their effects are included,the conditions favor a nuclear explosion.it will be completelydestroyed,it saves som e of the stars matter from being devoured by theblack hole.The explosion is powerful enough to hurl m

26、uch of the star*s matterout of the black hole，s reach,he says.The devouring of stars by blackholes m ay already have been observed,although at a m uch later stage.It isthought mat several months after the event that rips the star apart,itsmatter starts swirling into the hole itself.It heats up as it

27、 does so,releasing ultraviolet light and X-rays.If stars disrupted near black holesreally do explode,then they could in principle allow these events to bedetected at a m uch earlier stage,says Jules Hatpern of Columbia University inN ew York,U S 2.may m ake it possible to see the disruption of that

28、starimmediately if it gets hot enough,Brassart agrees.it can be observed in theX-rays and g am m a rays,but i t s something that needs to be morestudied,researcher Chris Fryer of the Los Alamos National Laboratory in LosAlamos,N e w Mexico,U S 3,says the deaths of these stars are difficult tosimulat

29、e,and he is not sure whether the researchers have proven their casethat they explode in the process.11.Something destructive could happen to a sta r that gets too close to ablack hole.Which of the following destructive statements is N O T mentioned inthe passage?A The black hole could tear apart the

30、 star.B The black hole could trigger a nuclear explosion in the star.C Theblack hole could dwindle its size considerably.D The black hole could devourthe star.12.According to the third paragraph,researchers differed from each other inthe problem o f.A whether nuclear reaction would occurB whether th

31、e stars would increase its density and temperature C whethershock waves would occurD whether the uneven forces would fla tte n the stars 13.According to the fourth paragraph,which of the following is N O T true?AN o nuclear explosion would be triggered inside the star.B The sta r would bedestroyed c

32、ompletely.C M uch of the s ta r s matter thrown by the explosion would be beyond theblack hole*s reach.D The black hole would completely devour the star.14.What w ill happen several months a fte r the explosion of the star?A Thes ta r，s matter w ill move further away from by the black hole.B The bla

33、ckhole，s matter w ill heat up.C The torn star*s matter w ill swirl into the black hole.D The black hole*s matter w ill release u ltrav io le t lig h t and X-rays.15.According to the context,the word m e a n s.A confusion B tearingapart C interruption D flatten in g Our culture has caused most Americ

34、ans toassume not only that our language is universal but that the gestures w e useare understood by everyone.W e do not realize that waving good-bye is the w ayto sum m on a person from the Philippines to one*s side,or that in Italy andsome Latin-American countries,curling the finger to oneself is a

35、 sign offarewell.Those private citizen s who sent packages to our troops occupyingGermany after World War II and marked them GIFT to escape duty payments didnot bother to find out that Giftmeans poison in German.Moreover,we like tothink of ourselves as friendly,yet we prefer to be at least 3 feet or

36、 anarms length away from others.Latins and Middle Easterners like to comecloser and touch,which makes Americans uncomfortable.Our linguistic andcultural blindness and the casualness with which we take notice of thedeveloped tastes,gestures,customs and languages of other countries,are感 谢 您 的 阅 读，祝 您 生 活 愉 快。