回复：I94卡问题

１。入境时是J1,　i94卡上写的expiration date: D/S. 去年八月转成H1,问题：是否需要更换新的I94卡？
-- In my case, my H1 approval notice came with a new I94.

２。入境是H1,I94给的有效时间与H1一致 (eg. expiration date: 8/31/2004)， 三年后H1 延期, 旧的I94是否已经失效？是否需要更换新的I94卡？
---When you renew your status, a new I94 Card should be attached to the approval notice.

３。如何更换I94卡?
--- Once you leave U.S, you turn in your current I94. When you come back, you will be issued a new one.
Or as I said above, new I94 should come with the status renewal approval.