to move up and down.
to arrange things into different types or groups.
the high, steep side of a mountain or rock.
to come face-to-face with another person
to put something over or on something else.
to damage something by squeezing it very hard.
a pile of things, one on top of another.
to fall slowly, drop by drop.
break or fall apart into small fragments, especially over a period of time as part of a process of deterioration