如果你想避免麻烦，就必须保持沉默。

You must ___keep ___your ___mouth ___shut if you want to avoid problems.

她决定保持沉默以保护她的朋友。

She decided to ___keep ___her ___mouth ___shut to protect her friend.

在某些情况下，保持沉默很重要。

It's important to ___keep ___your ___mouth ___shut in certain situations.