a grain of wheat in a bushel of chaff

• 毫无结果； 无济于事

a grain of wheat in a bushel of chaff的用法和样例：

例句

1. The next two days were spent in fruitless parleys.
   其后两日是消磨于毫无结果的谈判中。
2. So far, the police investigation has drawn a blank.
   到目前为止警方的调查毫无结果。