marginal effeciency of investment

例句：

1. 1. The marginal efficiency of investment is a critical factor in determining the optimal allocation of resources.
   边际投资效率是决定资源最优配置的关键因素。
2. 2. The marginal efficiency of investment has been shown to increase with the level of education.
   研究表明，教育水平越高，边际投资效率越高。
3. 3. The marginal efficiency of investment can be improved by investing in research and development.
   通过投资研发，可以提高投资的边际效率。