The results have remained largely unchanged in five years of studies from the University of California,Davis.

VOA: special.2009.11.20

That is the longest period in United States history that the flag has remained unchanged.

VOA: special.2010.04.02

So they remain mostly unchanged in the hundreds of years since they were built.

VOA: special.2009.03.04

"We have genes inside our body that go back three billion years, largely unchanged.

VOA: standard.2010.04.16