他们之间有一种默契，不需要说出来。

There was an ___unspoken understanding between them that no words were needed.

他们之间有一种不言而喻的默契。

There was an ___unspoken understanding between them.

在我们家，帮忙做家务是大家都遵守的不成文规定。

In our family, helping with housework is an ___unspoken rule that everyone follows.