The person is in room A or room B的否定句是什么?

The person is not in room A and room B.
改否定句时be动词变否定形式,or变成and.
再问： 弄不清楚全部否定还是部分否定
再答： 在英语中all, both, every, everyone, everything, everybody, everywhere等与否定词not, no连用时，表示的是部分否定，而非全部否定。例如 ① I don’t know all of them. ② I don’t like both of the books. 若要表示全部否定，则应用相应得表示部分否定的否定词。例如 ① I know none of them. ② I like neither of the books.