It cannot be changed. The expression comes from the idea that water that has fallen over a dam cannot be brought back again.

VOA: special.2009.05.10

But the secretary also said senior officials are aware that past efforts have failed, and he said it is not clear whether the view in Tehran has changed.

VOA: standard.2009.05.05

"It has been a tour where we have seen things changed,".

VOA: standard.2009.10.12

The United States has recently changed its Burma policy from isolating the military government to direct engagement in hopes that it will improve its human rights and allow for democracy.

VOA: standard.2009.11.08

In his commencement address, President Obama told the cadets he believes the nature of the war in Afghanistan has changed since it began in 2001, but that it is no less important today.

VOA: standard.2010.05.22

she says she has witnessed great change - much of it good But she noted that many important things have not changed, including the aims and values that inspired the United Nations Charter.

VOA: standard.2010.07.06