回复：回复：回复：Pijiang, can you check out my issues?

For OPT to be valid before graduation, the I-20 must be valid at all time and you must register and meet the full-time student defined by your school internation office. Also if not yet finished course requirements (except thesis/dissertation), this OPT will be subject to 20 hours/week limit during the semester/quarter.

If you did not apply for graduation, your DSO can issue you another I-20 if you ask. You cannot let the i-20 expired unless you graduate before the expiration date.