I flew from USA to Toronto, Canada on Dec 18th. At Cincinati airport, the agent of the airline company took my I-94 card. I told her not to do it, but she insisted and told me I could not board the plane if I kept my I-94 card. It was her company's policy. So I gave it to her. Now I am in Canada. As most of the Chinese students, my F1 visa expired long time ago. I can still stay in Canada for less than 30 days, and return to USA without a new visa. But I just found out recently that I should keep the original I-94 card they took from me if I want to go back to USA with an expired visa. Othervise, I need to go apply for a new visa. I called the airline company, they seemed to know nothing about visas and I-94 cards, and I have to wait to see if they can find the I-94 card they took. Does anybody have any experience in this issue. Please give me some advise. Thank you very much!