回复：小白兔或其他能帮助的同学，7th year H1B延期应给三年，but只给了一年

If your PD is not current yet, you do have right to get 3 years, if PD current, it's hard to argue because 104(c) clearly stated 140 approval AND visa number unavailable. Although in practice, there are people get 3-year extension while PD current, such as people from Taiwan/HK and 140 category EB2), but if the officer only wants to give them one year, hard to appeal.