升降是指用起重机械吊起货物，通过垂直运动实现装卸。Lifting up and down refers to lifting goods with lifting machinery, loading and unloading are realized by vertical movement.
升降是指用起重机械吊起货物，通过垂直运动实现装卸。Lifting up and down refers to lifting goods with lifting machinery, loading and unloading are realized by vertical movement.
A.正确
B.错误
正确答案：正确