I can only talk about the fact I know.

來源: 於 2009-04-27 15:22:32 [舊帖] [給我悄悄話] 本文已被閱讀：次

Not as pricipal, it does not matter. Half years is a good time limit. But I am not sure if it is too risky, not to give your I-94 when boarding. Some said yes, some said it is illegal. The fact I happened to know, the person always handed in the I-94 when leaving US.
Please ask around.