The phrase "a key demonstration" is correct and usable in written English.
You can use it when referring to an important or significant example that illustrates a point or concept.
Example: "The experiment served as a key demonstration of the theory's validity."
Alternatives: "a crucial example" or "an essential illustration."
This element of the design isn't dramatic, but it's an absolutely key demonstration of architectural and urban civility that makes the Weston Library's public, full-access qualities immediately obvious.
The protesters, many wearing pink as a symbol of opposition among women to a war, carried placards and sang and chanted slogans in a low-key demonstration organized by a group called Code Pink, a play on the national color-coded security alert system.
With Thursday's key demonstration approaching on the 104th anniversary of the Mexican revolution, the authorities announced the cancellation of the annual military parade that usually fills the capital's central streets on that day.
Protesters had gathered outside Ferguson police headquarters late on Wednesday, in what was a relatively low-key demonstration.
But as a relatively low-key demonstration was breaking up after Mr Jackson's resignation, two St Louis County police officers were shot and injured by gunfire.
We planned an impromptu, low-key demonstration to protest the presence of the Confederate flag outside the Georgia Dome.
With these key demonstrations firmly in place, it is necessary to evaluate the reliability performance of vertical GaN devices on bulk GaN substrates.
Most of our key demonstrations rely on within-cell comparisons that were intended to remove effects of cellular heterogeneity, DiI labeling, etc.
The location, known as "G-Pool," was long the site of the popular "Dine With Shamu" experience, in which guests pay extra to have a tank-side lunch or dinner, with a more intimate and low-key demonstration by one of the park's orcas.
