回複:should I-94 be returned
It should.
You may ask the immigration officer to stamp your AP when you return.In addition, you may fill out a new I-94. The immigration officer may make a note on it. The bottom line is to get some proof of legal (re)entry.
In my case, I handed in I-94 at departure, and the immirgration officer didn't stamp my AP at re-entry. But I had no problem at the interview.