She reached the top of the hill and stopped _______ on a big rock by the side of the path.
若数据1、﹣2、3、x的平均数为2,则x=____.
I want to ____ ( by buy ) a pair of shoes.
如图所示,木块B与水平轻弹簧相连放在光滑的水平面上,子弹A沿水平方向射入木块后留在木块B内,入射时间极短,而后木块将弹簧压缩到最短.关于子弹和木块组成的系统,下列说法中正确的是( )