By single entry they said does it mean that after applying ones and successful the person might not apply again in the future if they wanted to visit the country again?, if this is what they meant is very wrong and this is somehow saying they don't need a nonimmigrants from Nigeria because is very obvious, something that's usually approved to be valid for years has now been kept for few months, which means that those who might be thinking about acquiring the United States citizens from nigeria will be very difficult for it to get approved, this is a sad news for the people who loves traveling to united states.