I don't know ---.A.what to say and to do B.what to say or do

答案是B
记住这个句型：not- - - - or - - - -
She is NOT a doctor OR a nurse.
He doesn't know A or B.
再问： OK,那如果有C选项：what to say or to do呢？
再答： 也是对的。问题是它们不应该放在一起供你选择。