You look as though you slept badly.

你好像没睡好觉。

They look as though they're heading for divorce.

他们看样子会离婚。

But say, you look as though you're ok.

但是，嘿，你看起来好像还行。

You look as though you know each other.

你们看起来像互相认识。

You look as though you know one another.

你们看起来像是互相认识。