共用题干Please Fasten Your SeatbeltsSevere turbulence（湍流）can kill aircraft passengers.Now,in test flights over the Rocky Mountains, NASA（美国航空航天局）engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it.Clear-air turbulence often catches pilots by surprise.Invisible to radar,it is difficult to forecast and can hurl（用力抛出去）passengers about the cabin.In December 1997 , one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 meters in a few seconds.However,passengers can avoid serious injury by fastening their seatbelts."It is the only antidote（对 策）for this sort of thing,"says Rod Bogue, project manager at NASA's Dryden Flight Research Center in Edwards,California.The Center's new turbulence detector is based on lidar,or laser-radar.Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air.The technique depends on the Doppler Effect（多普勒效应）.The wavelength of the light shifts according to the speed at which the particles are approaching.In calm air,the speed equals the plane's airspeed.But as the particles swirl（打漩） in rough air,their speed of approach increases or decreases rapidly.The rate of change in speed corresponds to the severity（激烈程度）of the turbulence.In a series of tests that began last month,a research jet flew repeatedly into、 disturbed air over the mountain ridges（山脉）near Pueblo , Colorado.The lidar detector spotted turbulence between 3 and 8 kilometers ahead, and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered.Bogue says that he had"a comfortable amount of time"to fasten his seatbelt.The researchers are planning to improve the lidar's range with a more powerful beam.The system could be installed on commercial aircraft in the next few years.The turbulence detector can tell the severity of the turbulence by measuring______.A:the speed of the planeB:the speed of the lightC:the number of particles in the airD:the changes of the particles'speed
共用题干
Please Fasten Your Seatbelts
Severe turbulence（湍流）can kill aircraft passengers.Now,in test flights over the Rocky Mountains, NASA（美国航空航天局）engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it.
Clear-air turbulence often catches pilots by surprise.Invisible to radar,it is difficult to forecast and can hurl（用力抛出去）passengers about the cabin.In December 1997 , one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 meters in a few seconds.
However,passengers can avoid serious injury by fastening their seatbelts."It is the only antidote（对 策）for this sort of thing,"says Rod Bogue, project manager at NASA's Dryden Flight Research Center in Edwards,California.
The Center's new turbulence detector is based on lidar,or laser-radar.Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air.The technique depends on the Doppler Effect（多普勒效应）.The wavelength of the light shifts according to the speed at which the particles are approaching.In calm air,the speed equals the plane's airspeed.But as the particles swirl（打漩） in rough air,their speed of approach increases or decreases rapidly.The rate of change in speed corresponds to the severity（激烈程度）of the turbulence.
In a series of tests that began last month,a research jet flew repeatedly into、 disturbed air over the mountain ridges（山脉）near Pueblo , Colorado.The lidar detector spotted turbulence between 3 and 8 kilometers ahead, and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered.
Bogue says that he had"a comfortable amount of time"to fasten his seatbelt.The researchers are planning to improve the lidar's range with a more powerful beam.The system could be installed on commercial aircraft in the next few years.
Please Fasten Your Seatbelts
Severe turbulence（湍流）can kill aircraft passengers.Now,in test flights over the Rocky Mountains, NASA（美国航空航天局）engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it.
Clear-air turbulence often catches pilots by surprise.Invisible to radar,it is difficult to forecast and can hurl（用力抛出去）passengers about the cabin.In December 1997 , one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 meters in a few seconds.
However,passengers can avoid serious injury by fastening their seatbelts."It is the only antidote（对 策）for this sort of thing,"says Rod Bogue, project manager at NASA's Dryden Flight Research Center in Edwards,California.
The Center's new turbulence detector is based on lidar,or laser-radar.Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air.The technique depends on the Doppler Effect（多普勒效应）.The wavelength of the light shifts according to the speed at which the particles are approaching.In calm air,the speed equals the plane's airspeed.But as the particles swirl（打漩） in rough air,their speed of approach increases or decreases rapidly.The rate of change in speed corresponds to the severity（激烈程度）of the turbulence.
In a series of tests that began last month,a research jet flew repeatedly into、 disturbed air over the mountain ridges（山脉）near Pueblo , Colorado.The lidar detector spotted turbulence between 3 and 8 kilometers ahead, and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered.
Bogue says that he had"a comfortable amount of time"to fasten his seatbelt.The researchers are planning to improve the lidar's range with a more powerful beam.The system could be installed on commercial aircraft in the next few years.
The turbulence detector can tell the severity of the turbulence by measuring______.
A:the speed of the plane
B:the speed of the light
C:the number of particles in the air
D:the changes of the particles'speed
A:the speed of the plane
B:the speed of the light
C:the number of particles in the air
D:the changes of the particles'speed
参考解析
解析：根据第二段第三句，再结合上文可知，clear-air turbulence指的是第二段第三段中的“unexpectedrough air"，又由于disturbed与rough意义相近，故选B。
根据二段最后一句可知，1997年12月份的晴空湍流导致1人死亡、100人受伤，可以说是造成了很多伤亡。
根据第四段最后一句可知，晴空湍流的强度与微粒速度的变化有关。
根据第五段最后一句可知，激光雷达探测器能够探测到前方3千米到8千米之间的晴空湍流，并且预测的晴空湍流的强度和持续时间与真实情况相符。这说明激光雷达探测器能成功地预测晴空湍流。
根据最后一段第二句可知，研究人员正计划改善激光雷达探测器，准备使用更强的电脉冲来提升激光雷达探测器的探测范围。
根据二段最后一句可知，1997年12月份的晴空湍流导致1人死亡、100人受伤，可以说是造成了很多伤亡。
根据第四段最后一句可知，晴空湍流的强度与微粒速度的变化有关。
根据第五段最后一句可知，激光雷达探测器能够探测到前方3千米到8千米之间的晴空湍流，并且预测的晴空湍流的强度和持续时间与真实情况相符。这说明激光雷达探测器能成功地预测晴空湍流。
根据最后一段第二句可知，研究人员正计划改善激光雷达探测器，准备使用更强的电脉冲来提升激光雷达探测器的探测范围。
相关考题：
听力原文：The foreign banks should have set up a representative office in China two years before they can apply for a branch.(2)A．The foreign banks should have set up a representative office.B．The foreign banks can't apply for a branch.C．The foreign banks can't expand business in China.D．The foreign banks are forbidden to set up a representative office.
共用题干Please Fasten Your SeatbeltsSevere turbulence（湍流）can kill aircraft passengers. Now,in test flights over the RockyMountains , NASA（美国航空航天局）engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it.Clear-air turbulence often catches pilots by surprise.Invisible to radar,it is difficult to forecast and can hurl（用力抛出去）passengers about the cabin. In December 1 997 , one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 meters in a few seconds.However,passengers can avoid serious injury by fastening their seatbelts.“It is the only antidote（对策）for this sort of thing,”says Rod Bogue,project manager at NASA's Dryden FlightResearch Center in Edwards,California.The centre's new turbulence detector is based on lidar,or laser radar. Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air. The technique depends on the Doppler effect.The wavelength of the light shifts according to the speed at which the particles are approaching. In calm air,the speed equals the plane's airspeed.But as the particles swirl（打漩）in rough air,their speed of approach increases or decreases rapidly .The rate of change in speed corresponds to the severity（激烈程度）of the turbulence.In a series of tests that began last month,a research jet flew repeatedly into disturbed air over the mountain ridges（山脉）near Pueblo , Colorado. The lidar detector spotted turbulence between 3 and 8 kilometers ahead,and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered.Bogue says that he had“a comfortable amount of time”to fasten his seatbelt. The researchers are planning to improve the lidar's range with a more powerful beam.The system could be installed on commercial aircraft in the next few years.We can infer from the fifth paragraph that______.A: the lidar detector can successfully forecast turbulenceB: researchers are not sure about the effectiveness of the lidar detectorC: passenger planes will be used in further experimentsD: no more test flights are needed
共用题干Please Fasten Your SeatbeltsSevere turbulence（湍流）can kill aircraft passengers. Now,in test flights over the RockyMountains , NASA（美国航空航天局）engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it.Clear-air turbulence often catches pilots by surprise.Invisible to radar,it is difficult to forecast and can hurl（用力抛出去）passengers about the cabin. In December 1 997 , one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 meters in a few seconds.However,passengers can avoid serious injury by fastening their seatbelts.“It is the only antidote（对策）for this sort of thing,”says Rod Bogue,project manager at NASA's Dryden FlightResearch Center in Edwards,California.The centre's new turbulence detector is based on lidar,or laser radar. Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air. The technique depends on the Doppler effect.The wavelength of the light shifts according to the speed at which the particles are approaching. In calm air,the speed equals the plane's airspeed.But as the particles swirl（打漩）in rough air,their speed of approach increases or decreases rapidly .The rate of change in speed corresponds to the severity（激烈程度）of the turbulence.In a series of tests that began last month,a research jet flew repeatedly into disturbed air over the mountain ridges（山脉）near Pueblo , Colorado. The lidar detector spotted turbulence between 3 and 8 kilometers ahead,and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered.Bogue says that he had“a comfortable amount of time”to fasten his seatbelt. The researchers are planning to improve the lidar's range with a more powerful beam.The system could be installed on commercial aircraft in the next few years. What does“clear-air turbulence”in Paragraph 1 probably mean?A: A not very rough storm.B: Unexpected disturbed air.C: A kind of visible storm.D: A storm over mountain ridges.
共用题干Please Fasten Your SeatbeltsSevere turbulence（湍流）can kill aircraft passengers. Now,in test flights over the RockyMountains , NASA（美国航空航天局）engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it.Clear-air turbulence often catches pilots by surprise.Invisible to radar,it is difficult to forecast and can hurl（用力抛出去）passengers about the cabin. In December 1 997 , one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 meters in a few seconds.However,passengers can avoid serious injury by fastening their seatbelts.“It is the only antidote（对策）for this sort of thing,”says Rod Bogue,project manager at NASA's Dryden FlightResearch Center in Edwards,California.The centre's new turbulence detector is based on lidar,or laser radar. Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air. The technique depends on the Doppler effect.The wavelength of the light shifts according to the speed at which the particles are approaching. In calm air,the speed equals the plane's airspeed.But as the particles swirl（打漩）in rough air,their speed of approach increases or decreases rapidly .The rate of change in speed corresponds to the severity（激烈程度）of the turbulence.In a series of tests that began last month,a research jet flew repeatedly into disturbed air over the mountain ridges（山脉）near Pueblo , Colorado. The lidar detector spotted turbulence between 3 and 8 kilometers ahead,and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered.Bogue says that he had“a comfortable amount of time”to fasten his seatbelt. The researchers are planning to improve the lidar's range with a more powerful beam.The system could be installed on commercial aircraft in the next few years. In December 1997,a United Airlines flight hit unexpected rough air,_______.A: causing a lot of damage to the planeB: throwing its passengers out of the cabinC: resulting in heavy casualtiesD: forcing the pilot to make an emergency landing
共用题干Please Fasten Your SeatbeltsSevere turbulence（湍流）can kill aircraft passengers. Now,in test flights over the RockyMountains , NASA（美国航空航天局）engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it.Clear-air turbulence often catches pilots by surprise.Invisible to radar,it is difficult to forecast and can hurl（用力抛出去）passengers about the cabin. In December 1 997 , one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 meters in a few seconds.However,passengers can avoid serious injury by fastening their seatbelts.“It is the only antidote（对策）for this sort of thing,”says Rod Bogue,project manager at NASA's Dryden FlightResearch Center in Edwards,California.The centre's new turbulence detector is based on lidar,or laser radar. Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air. The technique depends on the Doppler effect.The wavelength of the light shifts according to the speed at which the particles are approaching. In calm air,the speed equals the plane's airspeed.But as the particles swirl（打漩）in rough air,their speed of approach increases or decreases rapidly .The rate of change in speed corresponds to the severity（激烈程度）of the turbulence.In a series of tests that began last month,a research jet flew repeatedly into disturbed air over the mountain ridges（山脉）near Pueblo , Colorado. The lidar detector spotted turbulence between 3 and 8 kilometers ahead,and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered.Bogue says that he had“a comfortable amount of time”to fasten his seatbelt. The researchers are planning to improve the lidar's range with a more powerful beam.The system could be installed on commercial aircraft in the next few years. The turbulence detector can tell the severity of the turbulence by measuring_______.A:.the speed of the planeB:.the speed of the lightC:.the number of particles in the airD:.the changes of the particles' speed
共用题干Please Fasten Your SeatbeltsSevere turbulence（湍流）can kill aircraft passengers. Now,in test flights over the RockyMountains , NASA（美国航空航天局）engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it.Clear-air turbulence often catches pilots by surprise.Invisible to radar,it is difficult to forecast and can hurl（用力抛出去）passengers about the cabin. In December 1 997 , one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 meters in a few seconds.However,passengers can avoid serious injury by fastening their seatbelts.“It is the only antidote（对策）for this sort of thing,”says Rod Bogue,project manager at NASA's Dryden FlightResearch Center in Edwards,California.The centre's new turbulence detector is based on lidar,or laser radar. Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air. The technique depends on the Doppler effect.The wavelength of the light shifts according to the speed at which the particles are approaching. In calm air,the speed equals the plane's airspeed.But as the particles swirl（打漩）in rough air,their speed of approach increases or decreases rapidly .The rate of change in speed corresponds to the severity（激烈程度）of the turbulence.In a series of tests that began last month,a research jet flew repeatedly into disturbed air over the mountain ridges（山脉）near Pueblo , Colorado. The lidar detector spotted turbulence between 3 and 8 kilometers ahead,and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered.Bogue says that he had“a comfortable amount of time”to fasten his seatbelt. The researchers are planning to improve the lidar's range with a more powerful beam.The system could be installed on commercial aircraft in the next few years. The last paragraph tells us,among other things,that_______.A: the lidar detector needs improvementB: many airlines are interested in the systemC: passengers often forget to fasten their seatbeltsD: the lidar detector can be used in a wide range of areas
共用题干Solar StormAt the end of October 2003,a sudden solar storm hit the earth.A solar storm refers to the large amounts of charged particles released into space_________(1)the solar energyincreases.The release of the energy_________(2)place along with the activity of the sunspots with a cycle of 11 years.This time,the_________(3)of the storm exceeded expectations.This_________(4)of intense solar storm was caused by the eruption of a solar flare （闪光）and the ejection（喷发）of the solar corona（日冠）on October28, 2003. Large amounts of charged particles moved 150, 000,000 kilometers through space toward the _________(5)in 19 hours. They could affect aircraft roaming（漫游）in space.The high-energy particles will_________(6)some of the parts of an aircraft.They may also cause it to fail.High-energy particles can threaten the safety of an aircraft at a high orbit.If an aircraft orbits at a lower orbit,it is_________(7)because it is under the protection of the earth's magnetic field.A solar storm not only affects aircraft but also is a_________(8)to the environment and humans.The aerosphere and magnetic field of the earth can_________(9)humans from ultraviolet radiation and X-rays. While most of the X-rays are absorbed after they enter the aerosphere（大气层）,still a few can_________(10) the ground.The geomagnetic storm caused by this round of solar storm reaches its highest level on the two_________(11)of the earth,which affects electricity supply of North America. Overexposure to_________(12)threatens the health of passengers on planes flying over the Polar Regions.If we fly in the sky during such a solar storm,it_________(13)we receive ten times the X-ray radiation.It's really damaging.Scientists say a solar eruption is like the sun sneezing,which will make the earth _________(14)a cold.Though this natural force is irresistible,scientists can still _________(15)its movement accurately by monitoring.Facing successive solar storms, humans can't drop their guard._________(10)A:lose B:reach C:break D:prepare
A:North?wind Airlines.Can I help you?B:Hello,I′d like to_____56_____,please.A:May I have your name and_____57_____,please?B:My name is Daniel Adams and my flight number is 374.A:When are you leaving?B:_____58_____.A:And your destination?B:Buenos Aires.A:_____59_____,please...All right.Your seat is confirmed,Mr.Adams.You′11 be arriving in Buenos?Aires at 4 o′clock p.m.local time.B:Thank you.Can I pick up my ticket when I check in?A:Yes,but_____60_____at least one hour before departure time.第（58）题选A.Hold the lineB.flight numberC.ask a questionD.To New YorkE.May I have your nameF.reconfirm my seatG.please check inH.On May 11th
In Western Australia，there are around 450 aircraft maintenance engineers，most of______work in the Perth metropolitan area.A.themB.whomC.whichD.they
共用题干Please Fasten Your SeatbeltsSevere turbulence（湍流）can kill aircraft passengers.Now,in test flights over the Rocky Mountains, NASA（美国航空航天局）engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it.Clear-air turbulence often catches pilots by surprise.Invisible to radar,it is difficult to forecast and can hurl（用力抛出去）passengers about the cabin.In December 1997 , one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 meters in a few seconds.However,passengers can avoid serious injury by fastening their seatbelts."It is the only antidote（对 策）for this sort of thing,"says Rod Bogue, project manager at NASA's Dryden Flight Research Center in Edwards,California.The Center's new turbulence detector is based on lidar,or laser-radar.Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air.The technique depends on the Doppler Effect（多普勒效应）.The wavelength of the light shifts according to the speed at which the particles are approaching.In calm air,the speed equals the plane's airspeed.But as the particles swirl（打漩） in rough air,their speed of approach increases or decreases rapidly.The rate of change in speed corresponds to the severity（激烈程度）of the turbulence.In a series of tests that began last month,a research jet flew repeatedly into、 disturbed air over the mountain ridges（山脉）near Pueblo , Colorado.The lidar detector spotted turbulence between 3 and 8 kilometers ahead, and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered.Bogue says that he had"a comfortable amount of time"to fasten his seatbelt.The researchers are planning to improve the lidar's range with a more powerful beam.The system could be installed on commercial aircraft in the next few years.The last paragraph tells us,among other things,that____＿.A:the lidar detector needs improvementB:many airlines are interested in the systemC:passengers often forget to fasten their seatbeltsD:the lidar detector can be used in a wide range of areas
共用题干Please Fasten Your SeatbeltsSevere turbulence（湍流）can kill aircraft passengers.Now,in test flights over the Rocky Mountains, NASA（美国航空航天局）engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it.Clear-air turbulence often catches pilots by surprise.Invisible to radar,it is difficult to forecast and can hurl（用力抛出去）passengers about the cabin.In December 1997 , one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 meters in a few seconds.However,passengers can avoid serious injury by fastening their seatbelts."It is the only antidote（对 策）for this sort of thing,"says Rod Bogue, project manager at NASA's Dryden Flight Research Center in Edwards,California.The Center's new turbulence detector is based on lidar,or laser-radar.Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air.The technique depends on the Doppler Effect（多普勒效应）.The wavelength of the light shifts according to the speed at which the particles are approaching.In calm air,the speed equals the plane's airspeed.But as the particles swirl（打漩） in rough air,their speed of approach increases or decreases rapidly.The rate of change in speed corresponds to the severity（激烈程度）of the turbulence.In a series of tests that began last month,a research jet flew repeatedly into、 disturbed air over the mountain ridges（山脉）near Pueblo , Colorado.The lidar detector spotted turbulence between 3 and 8 kilometers ahead, and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered.Bogue says that he had"a comfortable amount of time"to fasten his seatbelt.The researchers are planning to improve the lidar's range with a more powerful beam.The system could be installed on commercial aircraft in the next few years.What does"clear-air turbulence"in Paragraph 1 probably mean?A:A not very rough storm.B:Unexpected disturbed air.C:A kind of visible storm.D:A storm over mountain ridges.
共用题干Please Fasten Your SeatbeltsSevere turbulence（湍流）can kill aircraft passengers.Now,in test flights over the Rocky Mountains, NASA（美国航空航天局）engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it.Clear-air turbulence often catches pilots by surprise.Invisible to radar,it is difficult to forecast and can hurl（用力抛出去）passengers about the cabin.In December 1997 , one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 meters in a few seconds.However,passengers can avoid serious injury by fastening their seatbelts."It is the only antidote（对 策）for this sort of thing,"says Rod Bogue, project manager at NASA's Dryden Flight Research Center in Edwards,California.The Center's new turbulence detector is based on lidar,or laser-radar.Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air.The technique depends on the Doppler Effect（多普勒效应）.The wavelength of the light shifts according to the speed at which the particles are approaching.In calm air,the speed equals the plane's airspeed.But as the particles swirl（打漩） in rough air,their speed of approach increases or decreases rapidly.The rate of change in speed corresponds to the severity（激烈程度）of the turbulence.In a series of tests that began last month,a research jet flew repeatedly into、 disturbed air over the mountain ridges（山脉）near Pueblo , Colorado.The lidar detector spotted turbulence between 3 and 8 kilometers ahead, and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered.Bogue says that he had"a comfortable amount of time"to fasten his seatbelt.The researchers are planning to improve the lidar's range with a more powerful beam.The system could be installed on commercial aircraft in the next few years.In December 1997,a United Airlines flight hit unexpected rough air______.A:causing a lot of damage to the planeB:throwing its passengers out of the cabinC:resulting in heavy casualtiesD:forcing the pilot to make an emergency landing
共用题干Please Fasten Your SeatbeltsSevere turbulence（湍流）can kill aircraft passengers.Now,in test flights over the Rocky Mountains, NASA（美国航空航天局）engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it.Clear-air turbulence often catches pilots by surprise.Invisible to radar,it is difficult to forecast and can hurl（用力抛出去）passengers about the cabin.In December 1997 , one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 meters in a few seconds.However,passengers can avoid serious injury by fastening their seatbelts."It is the only antidote（对 策）for this sort of thing,"says Rod Bogue, project manager at NASA's Dryden Flight Research Center in Edwards,California.The Center's new turbulence detector is based on lidar,or laser-radar.Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air.The technique depends on the Doppler Effect（多普勒效应）.The wavelength of the light shifts according to the speed at which the particles are approaching.In calm air,the speed equals the plane's airspeed.But as the particles swirl（打漩） in rough air,their speed of approach increases or decreases rapidly.The rate of change in speed corresponds to the severity（激烈程度）of the turbulence.In a series of tests that began last month,a research jet flew repeatedly into、 disturbed air over the mountain ridges（山脉）near Pueblo , Colorado.The lidar detector spotted turbulence between 3 and 8 kilometers ahead, and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered.Bogue says that he had"a comfortable amount of time"to fasten his seatbelt.The researchers are planning to improve the lidar's range with a more powerful beam.The system could be installed on commercial aircraft in the next few years.We can infer from the fifth paragraph that____＿.A:the lidar detector can successfully forecast turbulenceB:researchers are not sure about the effectiveness of the lidar detectorC:passenger planes will be used in further experimentsD:no more test flights are needed
Can I have a look at your letter, please?（）AExcuse me, you can'tBI'm afraid you can'tCI can't agree with youDYes, thank you
航空器第一次接触着陆道面的那一点。（）A、The point at which an aircraft first touch the surface of runway.B、The point at which an aircraft first touch down the surface of runway.C、The fix at which an aircraft first touch down the surface of runway.D、The fix at which an aircraft first touch the surface of runway.
单选题Why can all the astronauts sleep at the same time?AThey have to follow the same timetableBThe radio will take care of the aircraft for them.CThere are enough sleeping bags in the spacecraft.DThere is no need for them to watch over the spacecraft.
单选题Can I have a look at your letter, please?（）AExcuse me, you can'tBI'm afraid you can'tCI can't agree with youDYes, thank you
问答题Directions: In this part of the test, you will describe the picture on your screen in as much detail as you can. You will have 30 seconds to prepare your response. Then you will have 45 seconds to speak about the picture.Practice 1
问答题Directions: In this part of the test, you will give your opinion about a specific topic. Be sure to say as much as you can in the time allotted. You will have 15 seconds to prepare. Then you will have 60 seconds to speak.Practice 1 Some employers value education over work experience because they say it gives employees a more complete understanding of a specific field. Other employers prefer work experience, saying it proves the candidate can deal with real world challenges. Which do you think is better and why? Use specific reasons and examples to support your opinion.
单选题High speed aircraft is made of metals that can（）both high temperature and pressure.Astand byBput up withCwithholdDwithstand
单选题通话用语“WILL you pull over well to the left at the holding point，to let an aircraft with an ear lier slot time take off before you”可以看出接受指令的航空器（）A可以立即起飞B需要等待，让另一架航空器先起飞C起飞时间提前D左转避让另一架航空器