Maybe these students do not know the correct answers.

VOA: special.2009.09.13

"I do not know the volume. The volume is uncertain. There is a large uncertainty range around the 5000 barrels.

VOA: standard.2010.05.02

The jester said, "If these wise men do not know how to hide the moon, then the moon cannot be hidden."

VOA: special.2009.03.28

I do not know what else to do but make the best of a bad deal and shake hands over it."

VOA: special.2009.06.27

"Aylmer," said Georgiana, "I do not know what the cost would be to both of us to remove this birthmark.

VOA: special.2009.09.26

"Vice President Lyndon Johnson has left the hospital in Dallas, but we do not know to where he has proceeded.

VOA: special.2009.08.16

But we do know that the violence between the Earps and the Cowboys did not end at the OK Corral.

VOA: special.2010.02.15

The scientists say they do not know how the treatment would work with patients who have no sensation at all below the injury.

VOA: special.2011.06.01

Another is that we do not necessarily know what drives us to do the things we do.

VOA: special.2010.04.13

Carbon monoxide is called the silent killer because people do not know it is in the air.

VOA: special.2010.02.02

They do not know why da Vinci painted it, or how it ended up in the collection of French ruler Francis the First.

VOA: special.2010.06.23

How could I answer the child? I do not know what it is any more than he.

VOA: special.2009.04.12

What many people do not know is that it was meant sarcastically, as just the opposite.

VOA: special.2011.06.27

Doctors do not know exactly how the brain stimulation works to help patients with Parkinson's.

VOA: special.2009.02.03