母亲B2，申请延期，现在在等待结果中。如果现在回国可以买加拿大航空的票么？主要
是有一条有疑问,加拿大的ctp要求：
had a valid U.S. visa to enter the United States and have not overstayed the
period of time they were authorized to remain in the United States;
不知道现在算不算overstayed，护照上海关写的半年，现在肯定过了。如果延期下来了
，有区别么？ 多谢各位了
