这种情况是规则的一个例外。

This situation is an exception to the ___rule.

我通常在周日拜访我的父母。

I visit my parents on Sunday, as a ___rule.

通常，骑自行车的孩子在很小的时候就学习道路安全。

As a ___rule, children who ride bikes learn about road safety at a young age.