It was only a question of time before one of them broke through....

其中一人突破只是时间问题… … 。

And similarly, of course, if investment rises to a higher figure than formerly, it is only a question of time before the marginal efficiency of capital falls sufficiently to bring about a recession unless there are compensating changes in other factors.

同样，当然，如果投资增加到比以前更高的数字，除非其他因素发生补偿性变化，否则资本的边际效率下降到足以导致经济衰退只是时间问题。