My friend's parents arrived US last May with B2, and got 6 months legal stay from entry in US(old I-94 expire last November).Later, they extended their stay for another 6 months and extension got approved and their new I-94 card expiration date is May,2008. My friend want to know ,if parents do not return to china after this may and over stay, according to " 滞留超过一年，将被禁止入境十年；超过半年，是禁三年", when is the data can be calculated as overstay? started from last November(old I-94 expired) or this May?Thanks a lot.