| 1. | On a bright and clear day a 15-cm helio can be seen at 50 km .
在明朗的晴天，15厘米大小的回照光在50公里处能看到。 |
| 2. | This is equal to the free-fall acceleration at a height of 300 km above the earth .
这是在地面上空300km处自由下落的加速度。 |
| 3. | The lunar highlands are scarred by innumerable craters ranging up to 236 km in diameter .
在月球的高地上留下无数环形山，有的直径达236千米。 |
| 4. | However the rigidity argument applies only to the outer few hundred km of the moon's interior .
然而，这种刚性的论断只适用于月球外层几百公里。 |
| 5. | The thicker coal seams are located in a 10-15 km wide belt along which the channel meanders .
较厚的煤层位于河道发生弯曲的、宽10-15公里的地带内。 |
| 6. | In the far reaches of the solar system comets range from a few km to a few hundred km across .
在太阳系的广阔空间范围里，彗星的大小一般从几千米到几十万米。 |
| 7. | A passenger in an airplane would notice a marked change in the atmosphere on passing an elevation of 11 km .
飞机中的乘客在飞过一万一千米高空时会注意到一个显著的变化。 |
| 8. | The lower boundary of the region above which molecular diffusion dominates is 120 km altitude and is known as the turbopause .
分子扩散占主导地位的区域下界约在120公里处称为湍流层顶。 |
| 9. | The region of the atmosphere below 90 km has a nearly constant mean molecular mass, and is therefore called the homosphere .
90公里以下大气区域，具有一个接近恒定的平均分子质量，因此称为均匀层。 |
| 10. | The main valley-fill unit, which is above 450 km wide and 15 m thick, trends north-south and has been traced for 40km .
主要的河谷充填砂岩单元，宽在450公里以上，厚15米，往南北方延伸。已跟踪约40公里。 |
