plough the sand

• vi. 白费力气(徒劳无功)

plough the sand的用法和样例：

例句

用作不及物动词 (vi.)

1. He was really just ploughing the sand.
   他不过是在白费力气。
2. It is no use crying about the past.
   过去的事哭也是白费力气。