人造地球卫星在科研、国防等方面起着不可替代的作用．只要发射的技术高，就能使人造地球卫星（ ）
A．在地球赤道面离地面任意高度的圆轨道上，并且相对于地面永远是静止的
B．在与地球赤道共面的圆轨道上做匀速圆周运动，但相对地面不一定是静止
C．有可能在地球任一纬度线所决定的平面内，绕地球做匀速圆周运动
D．始终在某一经度圈所在的平面内运动，且轨道与该经度圈为同心圆，卫星相对地面静止
A、B卫星可以在地球赤道共面离地面任意高度的圆轨道上做匀速圆周运动，根据开普勒第三定律
=k可知，轨道半径不同，周期不同，根据理论计算可知只有高度h≈3.6×104km的卫星周期才与地球自转周期相同，相对于地球静止，成为地球的同步卫星．故A错误，B正确．R3 T2
C、卫星绕地球要做匀速圆周运动，其圆心必须是地心，否则卫星不能稳定，被地球的万有引力拉到赤道平面．故C错误．
D、由于地球的自转，经度圈也旋转，所以卫星不可能始终在某一经度圈所在的平面内运动，更不可能与地球同步．故D错误．
故选B
| 阅读理解 |
| John Carlin was a "jack-of-all-trades." He was an artist and writer. He taught himself five foreign languages. He was a leader among the deaf. John Carlin's father was a poor shoemaker. John did not need to do things that other children of his age had to do. John showed his talent for drawing early in life. He often drew pictures on the floor with chalk. John worked as a house painter when he was 12. His days were busy with work. However, he taught himself foreign languages at night. When he was 20, he went to New York to learn drawing. When he ran out of his money, he went to work again. But he would return to learn drawing whenever he could afford it. John was the first person to receive an honorary degree(荣誉学位) from Gallaudet. He beat all difficulties and became a successful American. |
| 1. The underlined phrase "jack-of-all-trades" may mean "__________" in Chinese. |
| A. 多面手 B. 生意经 C. 工作狂 D. 守财奴 |
| 2. John Carlin ________when he was young. |
| A. worked hard at school B. learned five languages at school C. didn't go to school D. walked around after school |
| 3. John showed his talent for drawing __________. |
| A. before 12 years old B. at the age of 12 C. when he was 20 D. in his early thirties |
| 4. John went to New York to learn drawing with money __________. |
| A. donated(捐赠) by an organization B. by selling his paintings C. that his parents gave him D. that he earned by himself |
| 5. "Gallaudet" in the last paragraph is probably the name of __________. |
| A. a college B. a hospital C. a man D. a factory |