VO was right, see details

The number of entry and the valid time given are dependent on the type of visa and the country of origin of the person. H4 for chinese will only have one entry. So is O1 (see: http://travel.state.gov/visa/reciprocity/Country%20Folder/C/China.htm). Last time, when I applied for O-1, the VO asked have you even left the US during the past ten years, I answered No. When I got the visa, I found it was for two entries and so I was able to go back to China for the first time, very much like a prisoner released from the jail.