| 1. | The comet is not bound and makes but one visit to the solar system .
慧星是不受约束的，只是来访问一次太阳系。 |
| 2. | Planetologists believe comets are the oldest relics in the solar system .
行星学家们认为，彗星是太阳系中最古老的残余物。 |
| 3. | The comet nucleus itself is too small to hold on to these gases through gravitation .
慧核本身太小，它的引力不足以束缚住这些气体。 |
| 4. | The night sky is occasionally host to the transient visitors known as comets and meteors .
夜空有时还接待如彗星和流星那样的过路来访者。 |
| 5. | The emperor's long beard streamed in the wind like the tail of a flaming red comet .
这位国王的长胡须迎风飘扬，宛如燃烧着的红色慧星的尾巴。 |
| 6. | They predicted accurately every eclipse of the moon and sun, the return of every comet .
他们正确地预报每一次月蚀和日蚀，每一次慧星的出现。 |
| 7. | He suggests that the earth may have been hit by a comet, or may have passed through the tail of a comet .
他说地球可能会遇到慧星或者穿过一个慧尾。 |
| 8. | Scientists want to study comets because they may be the oldest objects in our solar system .
科学家之所以要研究彗星，是因为它们可能是太阳系中最古老的星球。 |
| 9. | 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。 |
| 10. | Many scientists believe that lunar craters were formed by the collision of meteors and comets against the moon .
许多科学家相信，月球坑穴是流星和彗星碰撞月球所造成的。 |
