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1) If my I-485 has not approved after I graduate. Is my stauts still legal here after I graduate?
Reply: No, you would be out of status if the I-485 was not approved before you graduate.

2) If my I-485 got denied, do I have to leave immediately? or I have grace period to change my status?
Reply: Only if you have not graduated yet and your I-485 is denied would you be able to change status. If you graduate and the I-485 is denied and you have not changed status before then, you are out of status and have no grace period to do so.

3) If I want to apply higher degree after I graduate (assume my I-485 is still pending), can I do that? what status I would be (still F-1 or others?)
Reply: You can get another F-1 or H-4 since your husband is on H1 and you can attend school on either visa.

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