回複：485 RFE

D/S denpends on your I-20 expiration date or your F-1 status maintenance (eg. attend class with required credit hours, etc.). Because your master's i-20's ending date was 12/99, but you did not renew/extend it after that date, and thus you were out of status from 12/99 to 8/00 even if you continued to study for your Master's until 5/00. In other words, you did not have valid D/S from 12/99 to 8/00. That is a problem for your RFE and I have no a good idea for you, but you might ask the International office at your school to see how to fix this problem.