"constantly demonstrated" is correct and can be used in written English.
You can use it to show that something is occurring repeatedly or is being done over a period of time. For example, "She constantly demonstrated her commitment to social justice."
Google has constantly demonstrated its capacity to empower users in China and so has become a special target.
"Apollo was a remarkably intelligent dog who constantly demonstrated leadership... ...... Michael Potter says in a press release.
This will be achieved by a combination of improved customer and market segmentation capability, improved customer service processes and tools, and, significantly, specific customer-focused behaviors' being constantly demonstrated both internally and with external customers.
Europe can be strong only together – a fact Britain's travails now constantly demonstrate.
"MIT faculty and students constantly demonstrate amazing creativity," said Leon Sandler, executive director of the Deshpande Center.
In an era of insecure employment, we must constantly demonstrate our usefulness through frenetic doing, and time management can give you a valuable edge.
Whether describing the "buttery glow" of late sun on "dun-colored sandstone" or the "red termite mounds leaning like the ruined towers of miniature cities," he's constantly demonstrating that the natural world is as splendiferous as any fable.
Nationwide security reports released daily since January constantly demonstrate that southern Iraq has evolved from a war zone to a benign place where weeks often go by without a single shooting, or bombing.
Part of the power of quilts stems from the infinite ways they elucidate the nature of geometry, simply by constantly demonstrating how smaller shapes add up to larger, different ones.
But as Knussen and his superb cast, led by the tenor Martyn Hill as Taverner himself, with David Wilson Johnson as the Jester and Stephen Richardson as the King, constantly demonstrate, it is also wonderfully communicative, and the whole bundle of issues it confronts, religious, political and artistic, are as relevant today as in the 16th century, or when Davies composed the work in the 1960s.
The action had been promoted by a group of Seattle businessmen calling itself the Anti-Japanese League, whose president explained to a newspaper at the time: "They constantly demonstrate their ability to best the white man at his own game in farming, fishing and business.
