I knew very well that the problem was more complex than he supposed.

我很清楚这个问题比他料想的更复杂。

As a relationship becomes more established, it also becomes a good deal more complex.

当一段关系固定下来以后，它也会变得复杂得多。

Why become more complex?

为什么要变得更复杂？

Here more sedentary and more complex societies flourished.

在这里，更多的定居和更复杂的社会蓬勃发展。

First, people are living longer with a lot more complex needs.

首先，人们的寿命越来越长，需求越来越复杂。