Maria came ____ (猛冲,突进) down the stairs as soon as she heard her mother back home.
一小球从离地面50m高处的A点自由下落,经水平地面弹回后在离地20m高的B处被接住.在上述过程中小球通过的路程是____m;位移的大小是____m.
下列运算正确的是( )