With a tag: John told me that there wasn't anyone in the office

With a tag: John told me that there wasn't anyone in the office at that time， ______?
【正确答案】：didn’t he
【题目解析】：在反意疑问句中,当think的主语是第二或第三人称时，反义疑问句部分的主语应与主句的一致。