'Be quiet,' said the teacher.

“安静点！”老师说道。

《牛津词典》

Be quiet! He hasn't finished speaking.

安静！他还没有讲完。

《牛津词典》

Be quiet, I have something to say.

安静，我有话要说。

《牛津词典》

I shouldn't have brought you here.I'm so sorry. - What? What are you...- Just be quiet and stand behind me.

VOA: standard.other

Additionally, these products are specifically engineered to be ultra-quiet, which make them ideal for even the most noise-sensitive working environments.

ENGADGET: LaCie 2big, 4big Quadra drives hop the USB 3.0 bandwagon, give Macs 12TB of speedy storage

She said the number of customers - who would "obviously be cat lovers" - would be limited to maintain a "quiet environment" and sleeping cats would be left undisturbed.

BBC: Totnes cat cafe plan criticised by animal charity

Opponents reckon they have colluded in making up optimistic projections about the speed with which airlines will change to yet-to-be-built clean, quiet aircraft.

ECONOMIST: Business travel