There are traveling waves and there are standing waves.

行波和驻波。

麻省理工公开课 - 固态化学导论课程节选

And so there are only two kinds of waves that can exist on this violin string, standing or traveling.

由于这只有两种波,可以存在在这条弦上，驻波或行波。

麻省理工公开课 - 固态化学导论课程节选