Nevertheless many discussions of this subject seem to be mainly concerned with the physical productivity of capital in some sense, though the writers fail to make themselves clear.

然而，关于这个主题的许多讨论似乎主要关注资本在某种意义上的物质生产力，尽管作者们没有说清楚。

Chapter vi of Professor Carver's Distribution of Wealth clearly envisages interest as the factor which brings into equilibrium the marginal disutility of waiting with the marginal productivity of capital.

Carver 教授的财富分配第六章清楚地将利息设想为使等待的边际负效用与资本的边际生产力达到平衡的因素。