I'd never have breathed a syllable if he'd kept quiet.

如果他当时保持沉默的话，我决不会说一个字的。

[no obj., with complement]she could have had some boyfriend she kept quiet about

她可能有过一位她始终缄口不提的男朋友

All kept quiet and change subjects.

欧洲所有人都保持沉默或者改变话题。

Matt Bomer has long kept quiet about his private life.

Matt Bomer长久以来对于自己的感情生活总是守口如瓶。

And you may know why I kept quiet with smile sometimes.

你们也许能因此明白为什么我有时候会带着微笑而保持沉默。

Or have you kept quiet when you were having trouble in class?

或者当你课堂上遇到困难时，保持安静？

If I had any sense then, I would have kept quiet about this matter.

如果当时我有点理智的话，我就会对这事保持沉默。

But he kept quiet, because he had heard what the alchemist said to the monk.

但没有开口，因为刚才他听到了炼金术士对修士说的话。

Tom Hiddleston and Taylor Swift have kept quiet about their relationship since they got together.

自抖森和霉霉恋爱以来，他们一直闭口不谈恋情的事（恩，你们没谈，你们只是秀了旁人一脸）。

Suddenly, there was a great splashing sound and the oyster closed his shell and very quickly kept quiet.

突然，传来一声巨响，溅起无数水花，牡蛎马上合上壳，不作声了。