单选题Geological evidence suggests that the earth’s magnetic polarity has switched back and forth many times over the millennia; such ______in the magnetic field may affect the ability of our planet to ward off cosmic radiation.AintensificationsBjustificationsCrecordsDcorrelationsEfluctuations
单选题
Geological evidence suggests that the earth’s magnetic polarity has switched back and forth many times over the millennia; such ______in the magnetic field may affect the ability of our planet to ward off cosmic radiation.
A
intensifications
B
justifications
C
records
D
correlations
E
fluctuations
参考解析
解析：
地球的磁极在过去一千年不断地变换，即为磁极不断变动，fluctuation“变动；起伏”，故选E。correlation是“相关，关联”的意思。
地球的磁极在过去一千年不断地变换，即为磁极不断变动，fluctuation“变动；起伏”，故选E。correlation是“相关，关联”的意思。
相关考题：
Permanent magnetism is caused by ______.A.operation of electrical equipment and generators on board shipB.the earth's magnetic field affecting the ship's hard iron during constructionC.the horizontal component of the earth's magnetic field acting on the horizontal soft ironD.the vertical component of the earth's magnetic field acting on the vertical soft iron
The direction of prevailing winds in the Northern hemisphere is caused by the ______．A.Magnetic field at the North PoleB.Gulf StreamC.Earth's rotationD.Arctic cold fronts
A ship under construction or major repair will acquire permanent magnetism due to ______ while sitting stationary in the earth's magnetic field．A.hammering and jarringB.vibration and poundingC.varying magnetic fieldsD.stable or permanent magnetism of the ship
Compass deviation is caused by ______.A.magnetism from the earth’s magnetic fieldB.misalignment of the compassC.magnetism within the vesselD.a dirty compass housing
Deviation in a compass is caused by the ______.A.vessel’s geographic positionB.vessel’s headingC.earth’s magnetic fieldD.influence of the magnetic materials of the vessel
Generally speaking, you should expect to find low atmospheric pressure prevailing in the earth’s ______.A.equatorial areaB.polar regionsC.mid-latitudesD.All of the above
If a magnetic compass is not affected by any magnetic field other than the Earth’s which statement is TRUE?______.A.Compass error and variation are equalB.Compass north will be true northC.Variation will equal deviationD.There will be no compass error
共用题干第一篇The Northern LightsThe sun is stormy and has its own kind of weather.It is so hot and active that even the Sun's gravity cannot hold its atmosphere in check!Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour.These particles are called plasma （等离子体）,and the stream of plasma coming from the Sun is called the solar wind.The more active the Sun,the stronger the solar wind.The solar wind constantly streams toward the Earth,but don't worry because a protective magnetic field surrounds our planet.The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles.The charged particles become trapped in magnetic belts around the Earth.When a large blast of solar wind crashes into the Earth's magnetic field,the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into tile Earth's atmosphere at the poles.As the electrons fall to the Earth,they collide with gas molecules in the atmosphere,creating flashes of light in the sky.Each atmospheric gas glows a different color.Oxygen and nitrogen glows red and green arid nitrogen glows violet purple.As these various colors glow and dance in the night sky,they create the Northern Lights and the Southern Lights.Watching auroras（北极光）is fun and exciting, but normally you can only see them in places far north like Alaska and Canada.The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate（跳动）,flicker（闪烁）,or even move like waves.During solar maximum,5 auroras are seen as far south as Florida,even Mexico!Auroras often seem to be very close to the ground,but the lowest aurora is still about 100 kilometers above the ground,a distance much higher than clouds are formed or airplanes can fly.A typical aurora band can be thousands of kilometers long,a few hundred kilometers high,but only a few hundred meters thick.We hope you are able to travel to far north places like the Arctic Circle and see the Northern Lights at least once during your lifetime.We know you will never forget it!What happens when solar wind comes to the Earth?A:It is trapped in magnetic belts around the Earth.B:A protective magnetic field is formed at the same time.C:It destroys the protective magnetic field surrounding the Earth.D:It breaks magnetic field lines and does severe damage to the Earth.
单选题According to the passage, the Earth’s magnetic field has _____.Abegun to change in the opposite directionBbeen weakening in strength for a long timeCcaused the changes on the polaritiesDmisguided many a man and animal
单选题Deviation is caused by（）.Achanges in the earth's magnetic fieldBnearby magnetic land masses or mineral depositsCmagnetic influence inherent to that particular vesselDthe magnetic lines of force not coinciding with the lines of longitude
单选题Compass deviation is caused by（）.Amagnetism from the earth's magnetic fieldBmisalignment of the compassCmagnetism within the vesselDa dirty compass housing
单选题According to the experts, the reversal of the Earth’s magnetic field would _____.Adestroy almost all the creatures on the EarthBcause some species extinctions on the EarthCnot be as disastrous as the previous oneDcause no big trouble for man and animals
单选题The magnetic compass magnets are acted on by the horizontal component of the Earth’s total magnetic force. This magnetic force is GREATEST at the（）.Anorth magnetic poleBsouth magnetic poleCmagnetic prime vertical meridianDmagnetic equator
单选题Which statement about the Flinders bar of the magnetic compass is CORRECT（）.AIt compensates for the error caused by the vertical component of the Earth's magnetic fieldBIt compensates for error caused by the heeling of a vesselCIt compensates for quadrantal deviationDIt is only needed in equatorial waters
单选题If a magnetic compass is not affected by any magnetic field other than the Earth’s，which statement is TRUE? （）ACompass error and variation are equalBCompass north will be true northCVariation will equal deviationDThere will be no compass error
单选题A plane perpendicular to the polar axis will never form what line on the Earth’s surface? （）AGreat circleBEquatorCSmall circleDMeridian
单选题During the transition of the Earth’s magnetic field _____.Athe compass will become uselessBman and animals will be confused as to directionsCthe magnetic strength of the Earth will disappearDthe magnetic strength of the Earth will be stronger
单选题Variation in a compass is caused by（）.Aworn gears in the compass housingBmagnetism from the earth's magnetic fieldCmagnetism within the vesselDlack of oil in the compass bearings
单选题According to the passage, _____.Awe should not worry about the transition of the Earth’s magnetic fieldBthe Earth’s magnetic field will not change for at least 2000 yearsCthe Earth’s magnetic field has decreased its strength rapidlyDthe transition of the Earth’s magnetic field can be controlled by modern science
单选题What is an advantage of the magnetic compass aboard vessels?（）ACompass error is negligible at or near the earth's magnetic polesBIt does not have to be checked as oftenCIt is reliable due to it's essential simplicityDAll points on the compass rose are readily visible
单选题What is the basic principle of the magnetic compass（）.AMagnetic materials of the same polarity repel each other and those of opposite polarity attractBThe Earth's magnetic lines of force are parallel to the surface of the EarthCMagnetic meridians connect points of equal magnetic variationDThe compass needle（s）will，when properly compensated，lie parallel to the isogonic lines of the Earth
单选题The magnetic compass operates on the principle that（）.Alike magnetic poles attractBunlike magnetic poles repelCunlike poles attractDthe poles of the compass line up with the geographic poles of the earth
单选题Permanent magnetism is caused by（）.Aoperation of electrical equipment and generators on board shipBthe earth's magnetic field affecting the ship's hard iron during constructionCthe horizontal component of the earth's magnetic field acting on the horizontal soft ironDthe vertical component of the earth's magnetic field acting on the vertical soft iron
单选题A ship under construction or major repair will acquire permanent magnetism due to（）while sitting stationary in the earth’s magnetic field.Ahammering and jarringBvibration and poundingCvarying magnetic fieldsDstable or permanent magnetism of the ship
单选题The directive force of a gyrocompass（）.Aincreases with latitude，being maximum at the geographic polesBdecreases with latitude，being maximum at the geographic equatorCis greatest when a vessel is near the Earth's magnetic equatorDremains the same at all latitudes
单选题The points on the earth’s surface where the magnetic dip is 90° are（）.AAlong the magnetic equatorBConnected by the isoclinal lineCThe isoporsDThe magnetic poles
单选题At the magnetic equator there is no induced magnetism in the vertical soft iron because（）.Athe lines of force cross the equator on a 0°-180°alignmentBthe quadrantal error is 0°Cthere is no vertical component of the Earth's magnetic fieldDthe intercardinal headings have less than 1°