假设火星和地球都是球体,火星的质量 M火和地球的质量M地之比为p,火星的半径R火和地球的半径R地之比为q,那么火星表面处的引力加速度和地球表面处的引力加速度之比等于 ( )
——The two old friends were ______ busy _____with each other ______ the time.——Yes. They haven't met for long.
These are my hand.
____应改为____