marginal rate of return over cost

例句：

1. 1.The company's marginal rate of return over cost is a key metric for evaluating its performance.
   该公司的边际回报率超过成本是评估其表现的关键指标。
2. 2. The investment had a marginal rate of return over cost of 20%.
   这项投资的边际回报率超过了20%。
3. 3. The new product line has a marginal rate of return over cost of 30%.
   新产品线的边际回报率超过了30%。