The phrase "advertisements over a" is correct and usable in written English.
It can be used when discussing the placement or context of advertisements, often in relation to a medium or platform.
Example: "We saw many advertisements over a variety of social media channels during the campaign."
Alternatives: "ads across a" or "commercials on a".
One hundred and twenty participants will be recruited from posters and leaflets placed in South London GP surgeries, menopause and breast-screening clinics, a menopause website (Menopause Matters) and newspaper advertisements over an 18-month period from March 2009 to May 2010.
"THEY said you couldn't create islands in the middle of a city," shouts a property advertisement over a jammed Dubai motorway.
While the current version is one-way, delivering the program guide and some advertisements over broadcast signals, a new system will be introduced next year that embeds two-way radios into each television.
Worse, with people unwilling to pay for news, organizations draw a large chunk of earnings from government advertisements, handing over a level of control.
The advertisements run over a three week period and, in addition to showing pictures of a family being robbed at gunpoint, say: "The State Assembly is considering a bill to make gun ownership illegal.
They came at barely more than two an over, a dreadful advertisement for drop-in pitches.
Tacitly acknowledging his vulnerability to harsh portrayals in a barrage of Mr. Bush's advertisements over the past month, Mr. Kerry urged Democrats at a $25,000-a-plate breakfast at the "21" Club in Manhattan to help him paint his own portrait.
All week, the Wisconsin contest has played out largely on the airwaves, as Mr. Obama and Mrs. Clinton ran a series of dueling television advertisements over Mr. Obama declining to appear alongside Mrs. Clinton in a debate.
There is an exhibit displaying advertisements over the years and another that shows the evolution of Jell-O's three-ounce package (the shape of which has not changed all that much).
"Wish You Were Here," one advertisement exults over a photograph of an idyllic marsh that looks like a Louisiana bayou, adding at the bottom: "WAIT!
