The phrase "a demonstration at a" is correct and usable in written English.
It can be used when referring to an event or activity where something is being shown or explained, typically in a public setting.
Example: "We organized a demonstration at a local park to showcase the new recycling program."
Alternatives: "a presentation at a" or "an exhibition at a".
Even gossiping with friends about relationships as the police move in to break up a demonstration at a dam site.
During a demonstration at a European trade show, for example, the technology had a well-publicized failure.
"It was fun to go almost as though you were going to a demonstration at a technological trade show.
The police watchdog has launched an investigation into allegations that officers assaulted students during a demonstration at a university that called for the scrapping of tuition fees.
He said that he picked up yodelling after he caught a troupe of Swiss emissaries doing a demonstration at a church.
But many employers have attacked the union's tactics as confrontational and heavy-handed, criticizing in particular a demonstration at a building manager's house.
Would Vice-President-elect Pence be able to arrange for a demonstration at an off-site location?
The fine tenor Gregory Kunde sang intensely as Tamas, whose cry for liberty in an aria is said to have incited a demonstration at an early performance.
MOSCOW — A Russian court ordered on Thursday that 22 Greenpeace activists, including an American ship captain and a photographer who was accompanying the group, be held in custody for two months while the authorities investigate whether a demonstration at an offshore oil rig in the Arctic was an act of piracy.
Cameras in Cardiff city centre and at a demonstration at an "arms fair" were used to gather the images of members of the public.
The Scorpion followed its Farnborough appearance with a demonstration at an exercise in Textron's home state of Kansas, designed to simulate the aftermath of a natural disaster (a major tornado strike) on the region.
