Now she's upset—why couldn't you keep your mouth shut?

瞧她现在心烦意乱的样子—你就不能闭上嘴？

《牛津词典》

I don't have to tell you how important it is for you to keep your mouth shut about all this.

我不必告诉你对这件事保密有多么重要。

《柯林斯英汉双解大词典》

You don't know the facts, so keep your mouth shut!

你不了解情况， 别多嘴!

《新英汉大辞典》

They warn that "a health care crisis is not the time to keep your mouth shut, " but rather a critical time to speak up and be your own advocate.

WSJ: The Health Reader: Listen Up, Doc

Any Slingbox model will get the job done, and other than that, you basically just have to be able to keep your mouth shut, fill out some forms, and enjoy plenty of placeshifted teevee.

ENGADGET: SlingPlayer Mobile for Symbian in private beta Mobile

Then his answer, because you couldn't keep your freaking mouth shut.

NPR: 'King Kong': Not Suitable for Children