To stop a problem you have to understand its underlying causes.

要杜绝一个问题，你就必须认识其根本成因。

I think that the underlying problems are education, unemployment, and bad housing.

我认为潜在的问题是教育、失业和恶劣的居住条件。

hills with the hard underlying rock poking through the turf.

从草皮下凸出来的坚硬岩石堆成的山峦。