The phrase "acting quietly" is correct and usable in written English.
It can be used to describe someone who is performing an action in a subdued or low-key manner, often to avoid drawing attention.
Example: "She was acting quietly during the meeting, making sure not to interrupt anyone."
Alternatives: "behaving discreetly" or "conducting oneself silently".
Adding to the effort, some of the most powerful American oil companies have been acting quietly on Azerbaijan's behalf.
So instead of acting quietly and efficiently, it unleashes a mighty storm, which fulfils the terrorists' most cherished dreams.
American special forces, who already train Yemeni counter-terrorist units, are said to be preparing for more direct action against al-Qaeda.None of this in itself explains why the White House made such a dramatic public statement of its anxieties, rather than acting quietly to thwart the plot when it heard of it.
In the Charmides, Charmides suggests that temperance consists in acting quietly.
But if you notice that this person is only acting quietly towards you and not towards others for an extended period of time, then you may have reason to be concerned.
Subtle feats of acting that quietly satirize Japan's homogeneity and emphasis on conformity, these images are initially innocuous.
In situations such as these, the regime, unwilling to be accused of acting against Islam, quietly turns a blind eye pretending to see and hear nothing.
The Internal Revenue Service, acting with unusual speed, quietly issued a ruling on Oct. 30 closing that loophole.
Ms. de Lavallade, who has had careers in acting and in dance, quietly emerges from the back, drawing the eye immediately.
Polly Teale's production is intensely intimate, with quietly superb ensemble acting, played out around a grim steel bunk bed.
Easy is a small series about small stories told quietly, and having Legolas acting smug front and centre feels unnecessarily distracting.
