It is quite common for small children to wet their beds.

小孩尿床是常有的事。

It's quite common, you know.

你知道吗？其实这很平常。

And it's a quite common response.

这个回应非常普遍。

The first scenario is quite common.

第一个模式很常见。

I take it that fear of death is quite common.

我想对死亡的恐惧是很常见的。