diminishing returns
noun [ plural ] uk/dɪˌmɪn.ɪʃ.ɪŋ rɪˈtɜːnz/ us/dɪˌmɪn.ɪʃ.ɪŋ rɪˈtɝːnz/
收益递减（指增加某种生产要素投入的同时，所得到的产量增加量递减的一种现象）
The law of diminishing returns refers to a situation in which a smaller result is achieved for an increasing amount of effort.