托福-54及答案解析.doc
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1、托福-54 及答案解析(总分:119.88,做题时间:90 分钟)一、READING(总题数:0,分数:0.00)二、Set 1(总题数:1,分数:8.00)FACTORS THAT INFLUENCE TIDES1 Tides are a natural phenomenon involving the alternating rise and fall in the earth“s large bodies of water caused by the gravitational forces of the moon and the sun. The combination of thes
2、e two variable forces produces the complex recurrent cycle known as the astronomical tides. Tides occur in oceans and seas, to a limited extent in large lakes and the atmosphere, and, to a very minute degree, in the earth“s solid crust. 2 The force that generates tides is the interaction of two diff
3、erent forces: the gravitational attraction of the moon acting upon the earth“s waters and the centrifugal force produced by the revolution of the earth around the center of gravity of the earth-moon system. Although the moon is only 384,395 kilometers from the earth, compared with the sun“s much gre
4、ater distance of 149,598,181 kilometers, the moon“s closer distance outranks its much smaller mass, and thus the moon“s tide-raising force is twice more than that of the sun. 3 The tide-generating forces of the moon and sun cause a maximum accumulation of the ocean waters at two opposite positions o
5、n the earth“s surface. This means that at any given time there are two high tides on the planet. One is the direct tide on the side facing the moon; the other is the indirect tide on the opposite side. At the same time these two high tides occur, compensating amounts of water are drawn from all poin
6、ts that are 90 degrees away from these bulges . As the earth rotates, a sequence of two high tides and two low tides is produced each day. Successive high tides occur about 12.4 hours apart. The direct high tide at any given location occurs when the moon is overhead; low tide occurs when the moon is
7、 at either horizon. 4 The highest and lowest levels of high tide, called spring tide and neap tide, each occurs twice in every lunar month of about 27.5 days. A spring tide occurs at the new moon and at the full moon, when the moon and earth are aligned with the sun, and thus the moon“s pull is rein
8、forced by the sun“s pull. At spring tide, the difference between high and low tides is the greatest. A neap tide, the lowest level of high tide, occurs when the sun-to-earth direction is at right angles to the moon-to-earth direction. When this happens, the gravitational forces of the moon and sun c
9、ounteract each other; thus, the moon“s pull is at minimum strength, and the difference between high and low tides is the least. Spring and neap tides at any given location have a range of about 20 percent more or less, respectively, than the average high tide. 5 The vertical range of tidesthe differ
10、ence between high and lowvaries according to the size, surface shape, and bottom topography of the basin in which tidal movement occurs. Typically, the tidal range in the open ocean is less than it is near the coasts. For example, in the open water of the central Pacific, the range is no more than 0
11、.3 meters, but in the relatively small, shallow North Sea, it is about 3.6 meters. Along the narrow channel of the Bay of Fundy in Nova Scotia, the difference between high and low tides may reach 16 meters under spring tide conditionsthe world“s widest tidal range. At New Orleans, which is at the mo
12、uth of the Mississippi River, the periodic rise and fall of the tides varies with the river“s stage, being about 0.24 meters at low stage and zero at high stage. In every case, actual high or low tide can vary considerably from the average. 6 Several physical factors influence tidal ranges, such as
13、abrupt changes in atmospheric pressure, prolonged periods of extreme high or low pressure, the density and volume of seawater, and variations in ocean-current velocities. Any of these factors alone can alter sea level; however, in combination with earthquakes, hurricanes, or other phenomena, they ar
14、e particularly forceful. Hurricane winds, for instance, can heap ocean water into powerful storm surges that increase the impact of the astronomical tides. When a storm surge coincides with the astronomical high tide, the resulting storm tide may reach up to six meters or more above the normal high
15、tide. The greater and more rapid the change of water level, the greater the erosive effect of the tidal action. Currents created by storm tides combine with the waves to erode beaches, coastal highways, and foundations of buildings.(分数:7.98)(1).The word recurrent in paragraph 1 is closest in meaning
16、 to(分数:0.57)A.repeatingB.mysteriousC.simultaneousD.interrupted(2).The force that controls tides on the earth is(分数:0.57)A.the gravitational pull of the planet“s coreB.the same force that generates tides on the moonC.abrupt changes in atmospheric pressureD.a combination of gravity and centrifugal for
17、ce(3).According to the passage, the moon(分数:0.57)A.has a greater density than the sunB.is closer to the sun than the earth isC.exerts a gravitational pull on the sunD.affects tides more than the sun does(4).The word bulges in paragraph 3 is closest in meaning to(分数:0.57)A.currentsB.intervalsC.increa
18、sesD.waves(5).What can be inferred from paragraph 3?(分数:0.57)A.The direct high tide is higher than the indirect high tide.B.When it is high tide in some places, it is low tide in other places.C.When the moon is directly overhead, the water is at its lowest level.D.At any given location, low tide occ
19、urs about 12 hours after high tide.(6).A spring tide occurs at the time of the lunar month when(分数:0.57)A.the moon“s gravitational pull is at its strongestB.the moon appears as a crescent or half-circleC.the sun does not exert any gravitational forceD.the vertical range of the tides is very narrow(7
20、).The word counteract in paragraph 4 is closest in meaning to(分数:0.57)A.enhanceB.signalC.opposeD.avoid(8).Which sentence below best expresses the essential information in the highlighted sentence in paragraph 4? Incorrect choices change the meaning in important ways or leave out essential informatio
21、n.(分数:0.57)A.The spring tide anywhere is around 20 percent higher than the normal high tide; the neap tide is 20 percent lower.B.In some places, there has been a 20 percent change in the number of spring tides and neap tides.C.If the location of a spring tide is known, then a neap tide in the same l
22、ocation will be 20 percent less.D.The spring tide in one location is always 20 higher than the neap tide in another location.(9).The author mentions the Bay of Fundy in paragraph 5 in order to(分数:0.57)A.compare the Bay of Fundy with larger bodies of waterB.explain why a narrow channel is dangerous f
23、or shipsC.give the most extreme example of a tidal rangeD.show how rivers can affect the rise and fall of tides(10).The word prolonged in paragraph 6 is closest in meaning to(分数:0.57)A.extendedB.surprisingC.predictedD.dangerous(11).All of the following are mentioned as influences on the vertical ran
24、ge of tides EXCEPT(分数:0.57)A.the size and shape of the water surfaceB.sudden changes in atmospheric pressureC.rising levels of ocean water pollutionD.abnormal water levels due to storms(12).In paragraph 6 the author makes the point that(分数:0.57)A.spring tides and storm surges are interrelatedB.storm
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- 托福 54 答案 解析 DOC