有人担心人口的补充问题。

There is a concern about replenishment of the population.

《柯林斯英汉双解大词典》

我的补充问题是：如果我们能够找出一个充分的理由，来解释以往西方的统治地位，那么我们能否对其未来做出一个预测呢？

My subsidiary question was this: If we can come up with a good explanation for the West 's past ascendancy, can we then offer a prognosis for its future?

youdao

要补充说明以下情况才合理，即他们是最后一刻才获知这个问题。

It's only fair to add that they were not told about the problem until the last minute.

《牛津词典》