2021年北师大大学考博英语真题试卷.pdf

2021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 6 8,做 题 时 间 9 0 分钟）1.R eading ComprehensionT he 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 hairs are stimulated by moving fluid.T heear can be divided into three regions:outer,middle,and inner.T he outer earcollects sound waves and directs them to the eardrum separating the outer earfrom the middle ear.T he middle ear conducts sound vibrations through threesmall bones to the inner ear.T he inner ear is a network of channelscontaining fluid that moves in response to sound or movement.T o performthe function of hearing,the ear converts the energy of pressure waves movingthrough the air into nerve impulses that me brain perceives as sound.V ibrating objects,such as the vocal cords of a speaking person,create wavesin me surrounding air.T hese waves cause the eardrum to vibrate with the samefrequency.T he 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.V ibrations of me oval window produce pressure 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.T he organ for balance is also located in the inner ear.S ensationsrelated to body position are generated much like sensations of sound.Haircells in the inner ear respond to changes in head position with respect togravity and movement.G ravity is always pulling down on the hairs,sending aconstant series of impulses to the brain.W hen the position of the headchanges-as when the head bends forward the force on the hair cells changesits output of nerve impulses.T he brain then interprets these changes todetermine the heads new position.1.W hat 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 fluid.D Both organs are located in me ears middle region.2.Hearing involves all of the following E X C E P T.A motion of the vocalcords so that they vibrate B stimulation of hair cells in fluid-filledchannels C amplification of sound vibrationsD conversion of wave energy into nerve impulses 3.It can be inferred from Paragraphs 2 and 3 that the cochlea is a partof.A the outer ear B me 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 air.C Gravity is a force that originates in the human ear.D Theorgan for hearing is not subject to gravity.5.In this 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 balanceThe geology of the Earth，s surface is dominated by the particularproperties 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 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 trickles down to form brooks,streams,and rivers,constituting whatis called the hydrographic network.This immense polarized network channelsthe water toward a single receptacle:an ocean.Gravity dominates this entirestep in the cycle because water tends to minimize its potential energy byrunning from high altitudes toward the reference point that is sea level.The rate at which a molecule of water passes through the cycle is not randombut is a measure of the relative size of the various reservoirs.If we defineresidence time as the average time for a water molecule to pass through one ofthe three reservoirsatmosphere,continent,and ocean-we see that the timesare very 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 last figure shows the importance of the ocean as the principalreservoir of the hydrosphere but also the rapidityof water transport on the continents.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 silicon stay wherethey are and form the thin,fertile skin of soil on which vegetation can grow.Sometimes soils are destroyed and transported mechanically during flooding.The erosion of the continents thus results from two closely linked andinterdependent processes,chemical erosion andmechanical erosion.Their respe。