Minton and Malhotra discuss several options, such as the possibility that planet-impacting asteroids may have a larger relative velocity than thought, and so make larger craters.

• 他们的入学是秘密 的，修学分也是秘密的，答辩也是秘密进行的。这些恶行恶状不仅严重造成了我 国高学历文凭的严重贬值，而且也严重损害了我国在世界学术界的形象。