Standing at the edge of the smooth rolled sand you could look up in the empty stands and see old women sweeping out the boxes.
站在碾平的沙地边，你向上面空荡荡的看台望去，可以看见几个老婆子正在清扫包厢。
2
Because the filters move with the plunger, the sweeping action of the fluid on the downstroke cleans the filters and keeps sand suspended within the production fluid.