Let us say I want to sell my car but I do not know exactly how much it is worth.

VOA: special.2009.04.12

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

VOA: special.2009.02.03

"You do not know how bad that is going to be. There have been children who have died from the swine flu,".

VOA: standard.2009.12.18

Dr.Vallenas says many mothers are discouraged from breast-feeding because they do not know how to get their baby to latch on properly to the breast's nipple, or because they suffer pain and discomfort.

VOA: standard.2009.08.01

How do we know that they are not going to keep it all?" The United States and allies France and Russia have supported the IAEA draft deal with Iran as a means to alleviate concerns that Tehran is using its nuclear program to develop atomic weapons covertly.

VOA: standard.2009.10.28