单项选择题

According to the second theory, why did the solar system clear everywhere except in the asteroid belt

A．The asteroid belt was too far away from the sun.
B．In the asteroid belt, the gravity of Jupiter was strong enough to balance the opposing pull of the sun.
C．The solar system prevented fragments from accreting into their own planets.
D．The asteroids are leftovers from the days of creation.

<上一题目录下一题>

热门试题

填空题

part role

问答题

The internet is, of course, the greatest problem for this century. The world will have to find a means, through some sort of international treaty or United Nations initiative, to control the material that’ s now going totally unregulated into people ’ s homes. That said, it will only take one little country like Paraguay to refuse to sign a treaty for transmission to be unstoppable. Parental control is never going to be sufficient. I’ m still very worried about the impact of violent video games, even though researchers say their impact is moderated by the fact that players don’ t so much experience the game as enjoy the technical maneuvers that enable them to win.