The phrase "act quietly" is correct and usable in written English.
You can use it when instructing someone to behave in a subdued or low-volume manner, often in situations where noise should be minimized.
Example: "During the presentation, please act quietly to avoid disturbing the speaker."
Alternatives: "behave silently" or "remain subdued."
If we act, we should act quietly.
Mosher, in what could be interpreted as a passive-aggressive act, quietly announced, "Ricky, you know, I also concentrated on a card".
Her response, in recent months, has been to try a delicate balancing act, quietly easing up on crisis-stricken states, giving them more time to narrow their budget deficits, while showing no outward signs of weakness that her political rivals can pounce upon.
If you ask what the aim of this war is, I will tell you: The aim of this war of terror, the aim of the terrorists, their aides and dispatchers, the aim of those who enable them to perpetrate their acts quietly without disturbance, is to expel us from here.
Men expressed their preference for women who acted quietly, asked for permission to go out, were obedient, and had few friends.
The Data Quality Act was quietly enacted in December 2000 as 27 lines in a giant budget bill.
Senator Marco Rubio, who is covered under the Affordable Care Act (ACA), quietly inserted a provision in this year's spending bill that prevents some insurance companies from recouping losses under the shared risk pool agreement.
Just as compass needles all point north without being told to, so these people instinctively know what is expected of them when the state's interests are under threat and they act accordingly, quietly suppressing uncomfortable evidence or undermining the credibility of witnesses whose evidence contradicts the official narrative.
WASHINGTON -- After significant public controversy over H.R. 3, the No Taxpayer Funding for Abortion Act, lawmakers quietly amended the legislation and removed some of its most controversial provisions.
Austrian live-electronic act HVOB quietly released its second album Trialog last week amidst a thread of stateside tour dates and little fanfare.
The act begins quietly, with Scarpia musing on the forthcoming downfall of Angelotti and Cavaradossi, while in the background a gavotte is played in a distant quarter of the Farnese Palace.
