坐在船上的人用桨向后划水时,船就会向前进,则在平静的水面上,使船前进的力是[ ]
A.人手作用在桨上的力
B.桨向后作用于水上的力
C.水作用于桨的力
D.水作用于船体的力
答案:C
She was so upset by the accident that she couldn't ________ to explain just what happened. [ ]
A. settle down
B. take down
C. put down
D. bring down
设立非限定性集合资产计划必须报经中国证券业协会的批准。( )