Strauss suggests asking the couple directly if they had not made themselves clear.

施特劳斯建议直接问这对夫妇，他们是否还没有说清楚。

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。