北京师范大学考博英语真题.docx

1、北京师范大学考博英语真题2015年北京师范大学考博英语真题(总分68, 做题时间90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 produce electrochemical impulses when the hairs are stimulated by moving fluid. The ear ca

2、n be divided into three regions: outer, middle, and inner. The outer ear collects sound waves and directs them to the eardrum separating the outer ear from the middle ear. The middle ear conducts sound vibrations through three small bones to the inner ear. The inner ear is a network of channels cont

3、aining fluid that moves in response to sound or movement. To perform the function of hearing, the ear converts the energy of pressure waves moving through the air into nerve impulses that me brain perceives as sound. Vibrating objects, such as the vocal cords of a speaking person, create waves in me

4、 surrounding air. These waves cause the eardrum to vibrate with the same frequency. The three bones of the middle ear amplify and transmit the vibrations to the oval window, a membrane on the surface of the cochlea, the organ of hearing. Vibrations of me oval window produce pressure waves in the flu

5、id inside me cochlea. Hair cells in the cochlea convert the energy of the vibrating fluid into impulses that travel along the auditory nerve to the brain. The organ for balance is also located in the inner ear. Sensations related to body position are generated much like sensations of sound. Hair cel

6、ls in the inner ear respond to changes in head position with respect to gravity and movement. Gravity is always pulling down on the hairs, sending a constant series of impulses to the brain. When the position of the head changesas when the head bends forwardthe force on the hair cells changes its ou

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

8、f fluid.D Both organs are located in me ears middle region.2. Hearing involves all of the following EXCEPT_.A motion of the vocal cords so that they vibrateB stimulation of hair cells in fluid-filled channelsC amplification of sound vibrationsD conversion of wave energy into nerve impulses3. It can

9、be inferred from Paragraphs 2 and 3 that the cochlea is a part of_.A the outer earB me eardrumC the middle earD the inner ear4. What can be inferred from Paragraph 4 about gravity?A Gravity has an essential role in the sense of balance.B The ear converts gravity into sound waves in the air.C Gravity

10、 is a force that originates in the human ear.D The organ for hearing is not subject to gravity.5. In this passage, the author mainly explains_.A the organs of the human earB the function of the hearingC the three regions of the earD how the ear organ performs the hearing and balanceThe geology of th

11、e Earths surface is dominated by the particular properties of water. Present on Earth in solid, liquid, and gaseous states, water is exceptionally reactive. It dissolves, transports, and precipitates many chemical compounds and is constantly modifying the face of the Earth. Evaporated from the ocean

12、s, water vapor forms clouds, some of which are transported by wind over the continents. Condensation from the clouds provides the essential agent of continental erosion: rain. Precipitated onto the ground, the water trickles down to form brooks, streams, and rivers, constituting what is called the h

13、ydrographic network. This immense polarized network channels the water toward a single receptacle: an ocean. Gravity dominates this entire step in the cycle because water tends to minimize its potential energy by running from high altitudes toward the reference point that is sea level. The rate at w

14、hich a molecule of water passes through the cycle is not random but is a measure of the relative size of the various reservoirs. If we define residence time as the average time for a water molecule to pass through one of the three reservoirsatmosphere, continent, and oceanwe see that the times are v

15、ery different. A water molecule stays, on an average, eleven days in the atmosphere, one hundred years on a continent and forty thousand years in the ocean. This last figure shows the importance of the ocean as the principal reservoir of the hydrosphere but also the rapidity of water transport on th

16、e continents. A vast chemical separation process takes places during the flow of water over the continents. Soluble ions such as calcium, sodium, potassium, and some magnesium are dissolved and transported. Insoluble ions such as aluminum, iron, and silicon stay where they are and form the thin, fer

17、tile 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 and interdependent processes, chemical erosion and mechanical erosion. Their respective interactions and effi

18、ciency depend on different factors.6. According to the passage, clouds are primarily formed by water_.A precipitating onto the groundB changing from a solid to a liquid stateC evaporating from the oceansD being carried by wind7. The passage suggests that the purpose of the hydrographic network is to

19、_.A determine the size of molecules of waterB prevent soil erosion caused by floodingC move water from the Earths surface to the oceansD regulate the rate of water flow from streams and rivers8. What determines the rate at which a molecule of water moves through the cycle, as discussed in the third

20、paragraph?A The potential energy contained in water.B The effects of atmospheric pressure on chemical compounds.C The amounts of rainfall that fall on the continents.D The relative size of the water storage areas.9. All of the following are examples of soluble ions EXCEPT_.A magnesiumB ironC potassi

21、umD calcium10. The word efficiency in line 21 is closest in meaning to_.A relationshipB growthC influenceD effectivenessScientists have long understood that supermassive black holes weighing millions or billions of suns can tear apart stars that come too close. The black hotels gravity pulls harder

22、on the nearest part of the star, an imbalance that pulls the star apart over a period of minutes or hours, once it gets close enough. Scientists say this uneven pulling is not the only hazard facing the star. The strain of these unbalanced forces can also trigger a nuclear explosion powerful enough

23、to destroy the star from within. Matthieu Brassart and Jean-Pierre Luminet of the Observatoire de Paris in Meudon, France, carried out computer simulations of the final moments of such an unfortunate stars life, as it veered towards a supermassive black hole. When the star gets close enough, the une

24、ven forces flatten it into a pancake shape. Some previous studies had suggested this flattening would increase the density and temperature inside the star enough to trigger intense nuclear reactions that would tear it apart. But other studies had suggested that the picture would be complicated by sh

25、ock waves generated during the flattening process and that no nuclear explosion should occur. The new simulations investigated the effects of shock waves in detail, and found that even when their effects are included, the conditions favor a nuclear explosion. There will be an explosion of the star i

26、t will be completely destroyed, Brassart says. Although the explosion obliterates the star, it saves some of the stars matter from being devoured by the black hole. The explosion is powerful enough to hurl much of the stars matter out of the black holes reach, he says. The devouring of stars by blac

27、k holes may already have been observed, although at a much later stage. It is thought mat several months after the event that rips the star apart, its matter starts swirling into the hole itself. It heats up as it does so, releasing ultraviolet light and X-rays. If stars disrupted near black holes r

28、eally do explode, then they could in principle allow these events to be detected at a much earlier stage, says Jules Hatpern of Columbia University in New York, US2. It may make it possible to see the disruption of that star immediately if it gets hot enough, he says. Brassart agrees. Perhaps it can

29、 be observed in the X-rays and gamma rays, but its something that needs to be more studied, he says. Supernova researcher Chris Fryer of the Los Alamos National Laboratory in Los Alamos, New Mexico, US3, says the deaths of these stars are difficult to simulate, and he is not sure whether the researc

30、hers have proven their case that they explode in the process.11. Something destructive could happen to a star that gets too close to a black hole. Which of the following destructive statements is NOT mentioned in the passage?A The black hole could tear apart the star.B The black hole could trigger a

31、 nuclear explosion in the star.C The black hole could dwindle its size considerably.D The black hole could devour the star.12. According to the third paragraph, researchers differed from each other in the problem of _.A whether nuclear reaction would occurB whether the stars would increase its densi

32、ty and temperatureC whether shock waves would occurD whether the uneven forces would flatten the stars13. According to the fourth paragraph, which of the following is NOT true?A No nuclear explosion would be triggered inside the star.B The star would be destroyed completely.C Much of the stars matter thrown by the explosion would be beyond the black holes reach.D The black hole would completely devour the star.14. What will happen several months after the