单选题 Ray: ______. Where was I?
Brenda: You were talking about your trip to South Africa.

【正确答案】 A

【答案解析】[解析] A项“Let"s back up. Where was I?”意思为“好吧，言归正传。我讲到哪儿啦?”，最符合本句话的语境。其他选项的表达法都不符合上下文的语境。