According to the passage why do the dust part
问题详情
According to the passage, why do the dust particles in a meteor stream eventually surround a comet’s orginla orbit？
A．They are ejected by the comet at differing velocities.
B．Their orbits are uncontrolled by planetary gravitational fields.
C．They become part of the meteor stream at different times.
D．Their velocity slows over time.
E．Their ejection velocity is slower than that of the comet.请帮忙给出正确答案和分析，谢谢！
参考答案
正确答案：A
解析：Thisquestionasksforthereasongiveninthepassageforacharacteristicfeatureofmeteorstreams.Accordingtolines1-7,thedustparticlesinameteorstreameventuallysurroundacomet’soriginalorbitbecauseofthedifferentvelocitiesatwhichtheyareejected,asstatedinchoiceA,thebestanswer.ChoiceBisdirectlycontradictedbyinformationinthepassage(lines8-10).Theotheranswerchoicesreincorrectbecausethepassagedoesnotsaythatthedustparticlesbecomepartofthemeteorstreamatdifferenttimes,orthattheirvelocityslowsovertime,orthattheirejectionvelocityisslowerthanthatofthecomet.
