Why does she use "either" not "both" here?
Native speaker’s answer
Rebecca
This is a great question. "Either" is used to refer only to ONE of TWO choices, or to select one out of two. "Both" is used to indicate the first and second choices together. In this context, the girl is asking whether anyone has seen Jane, not both of them together. Ex. I want to play either basketball or soccer. Ex. I want to play both basketball and soccer.