请教8老师，目前今天入境美国，没有入境卡，只在护照盖了个章，手写了B2，怎么知道离境时间？
-The duration of stay should be indicated on the stamp of visa page, and just check it carefully and you will find it.
还需要在网上填I-94表吗？
-No. If your mother wants to extend her B2 status later, she needs to find the I-94 at this website (print it out and enclose it with the B2 extension application). The I-94 expiration date will be the date she needs to leave US if she does not extend her B2 status:https://i94.cbp.dhs.gov/I94/request.html;jsessionid=zKG6SmnDr7lZybhvxN6WmcYj5sy0v95hXKySBBFF72l6j48vrC6Q!271044983
