问题 不定项选择

2010年1月17日,我国成功发射北斗COMPASS-G1地球同步卫星,据了解这已是北斗卫星导航系统发射的第三颗地球同步卫星。则对于这三颗已发射的同步卫星,下列说法中正确的是 [ ]

A. 它们的运行速度大小相等,且都小于7.9 km/s

B. 它们运行周期可能不同

C. 它们离地心的距离可能不同

D. 它们的向心加速度与静止在赤道上物体的向心加速度大小相等

答案

答案:A

单项选择题

Passage oneLong bus rides are like television shows .They have a beginning ,a Middle and an end –with commercials thrown in every three or four minutes .The commercials are unavoidable .They happen whether you want them or not .Every couple of minutes a billboard glides by outside the bus window . “buy super clean toothpaste”. “Drink Good’n Wet Root Beer .””Fill up with Pacific Gas .”Only if you sleep ,which site equal to turning the television set off ,are you spared the unending cry of “You Need It ! Buy It Now !” The beginning of the ride is comfortable and somewhat exciting ,Even if you’ve traveled that way before .usually some things have changed-new houses ,new buildings ,sometimes even a new road .The bus driver has a style of driving and it’s fun to try to figure it out the first hour or so . If the driver is particularly reckless or daring ,the ride can be an thrilling as a suspense story .Will the driver pass the truck in time Will the driver move into the right or the left –hand lane After a while,of course,the excitement dies down .sleeping for a while helps pass the middle hours of the ride .Food always makes bus rides more interesting .But you’ve got to be careful of what kind of foodyou eat .Too much salty food can make you very thirsty between stops. The end of the ride is somewhat like the beginning .You know it will soon be over and there’s a kind of expectation and excitement in that .The seat ,of course ,has become harder as the hours have passed.By now you’ve sat with you legs crossed ,with your hands crossed behind your head .the end comes just at the right time . There are just no more ways to sit.

According to the passage ,what do the passengers usually see when they are on a longBus trip( )

A.Buses on the road

B. Films on television

C.Advertisements on the board

D. gas stations

单项选择题