经济困难的

A less obvious application is that the minimum spanning tree can be used to approximately solve the traveling salesman problem.

不太显而易见的应用是，最小生成树可用于大约解决旅行商问题。

There are no voiced plosives stops in Hakka, but it exhibits two sets of stops, one unaspirated, and the other aspirated.

客家话中没有浊音的爆破音停顿，但是却有两组停顿其一是不送气的，其二是送气的。