A:岩浆活动
B:有大面积的花岗岩体
C:石英砂岩的长期风化侵蚀
D:花岗岩的球状风化过程
He has two sisters. One is a doctor and is a teacher.
从正在匀速上升的载人氢气球中掉下一重物,此后该重物的运动情况是( )