流水的侵蚀作用。
参考答案:
流动的水一方面侵蚀岩层,溶解岩石;
一方面摩擦床底和两岸谷壁,同时又推动泥沙、石块,撞击坡面和床底,使岩屑崩解,为流水所运移。
中国证券业协会自( )成立以来,共召开了( )次会员大会。
A.1991;2
B.1992:4
C.1991;4
D.1990;2
A person suffering from possible broken bones and internal injuries should().
A.be assisted in walking around
B.be examined then walked to a bunk
C.not be moved but made comfortable until medical assistance arrives
D.not be allowed to lie down where injured but moved to a chair or bunk