hey micky mouse, technically you can only stay outside the US not more than 6 months and up to a year with prior notification. but you're right as they don't have any way to track when you left (i should say they don't have standard tracking mechanism). the only way to check would be the date stamped on your nepali passport. so stay as long as you want in nepal....as long as your green card has more than 6 months left to the expiration date. all you've had to do on your way back is apply and come with a new nepali passport but make sure you tell the immigration back in the US you were only out for couple months