And she says it is important to her that her two daughters know about that part of their background.

VOA: special.2009.05.06

So energy expert Eric Potter says it is too early to know how the new gas shale reserves will affect the market.

VOA: special.2009.10.23

So what might those be? Political scientist John McGlennon at the College of William and Mary in Virginia says it is too soon to know.

VOA: special.2010.03.06

Global Witness director Simon Taylor says the end of the oil age will change life as we know it.

VOA: standard.2009.10.20

Colin Macpherson, a professor of Earth sciences at Britain's Durham University, says it's impossible to know how long the volcano will continue to erupt.

VOA: standard.2010.04.16

He says he believes it is necessary to let North Korea know having nuclear programs will prove to be a bigger disadvantage than not having them.

VOA: standard.2009.05.26

He says it is difficult to know how the disease will evolve.

VOA: standard.2009.05.14