题目

 He cooked a great meal to ______ the help of his neighbors in finding his lost little daughter.    A. acknowledge      B. thank     C. express   D. admit 答案：A物体从光滑的斜面滑下的过程中（不计空气阻力），受到的力有（ ）A．重力和支持力B．重力、支持力和下滑力C．重力、下滑力和摩擦力D．重力和下滑力