Their appearance changes endlessly with the light,the time of year, and the weather.

VOA: special.2009.10.07

After a long time, some of the rock changes to clay.

VOA: special.2009.09.14

The G20,which includes major industrialized powers in the Group of Eight plus developing nations with significant economies such as China and India, agreed to a specific time line for deficit reduction, while giving governments flexibility to adjust the pace of changes based on their own situations.

VOA: standard.2010.06.27