gnaw a file

• 徒劳无功

gnaw a file的用法和样例：

例句

1. It was the cold of his errand, a foot's errand.
   这是因为这趟奔走肯定徒劳无功而感到发冷吧。
2. We wasted all day on a wild-goose chase.
   我们徒劳无功的浪费了一整天。
3. To argue with such a marl is like beating the air.
   跟这号人辩论是白费力气。
4. It is of no use boasting of being rich on a desert island.
   在无人岛上夸耀富有也是白费力气。