母爱，是人类一个亘古不变的主题。

Mother love, is a human being eternally immutable subject.

youdao

这将是贯穿我们整个课程的，一个亘古不变的主题。

And this really is going to be a recurring theme throughout the course.

youdao

这期间有一个始终不变的主题，那就是学习文化知识。

There is a constant theme in this period, that is to learn cultural knowledge.

youdao

And this really is going to be a recurring theme throughout the course.

这将是贯穿我们整个课程的,一个亘古不变的主题。

哈佛公开课 - 计算机科学课程节选

This ambivalence that was part of his personal life, the way he lived, would be a constant theme in subsequent Russian and still, in many ways, is today.

这种矛盾成了他个人生活的一部分,他的这种矛盾的生活方式在接下来的俄国,即便是在今天的俄国也是个不变的主题

耶鲁公开课 - 欧洲文明课程节选