Comets造句怎么写

8、Comets are conglomerations of ice, dust and rock from the early solar system, whose cores have remained physically and chemically unchanged ever since.

2、Comets, by contrast, are relatively pristine - at least, below their outer crust.

4、Comets were formed around the same time the Earth was formed.

6、Comets are probably the most numerous astronomical bodies in the solar system aside from small meteor fragments and the asteroids.

1、Comets are similar in composition to the gas giants.

5、Comets consist of "dirty ice", rather than solid rock, and so contain little iridium.

3、 Comets are just as much members of the sun's family as (are) the other planets.

7、Comets formed in circular orbits but were gravitationally flung into their present-day elliptical orbits when they ventured too close to planets.