单选题 This is the second time that your mother has been to London, ______?
A. isn't she
B. isn't it
C. has she
D. hasn't she

【正确答案】 B

【答案解析】[解析] 本句的主句为It is the second time，主从复合句的反意疑问句附加疑问部分助动词与人称应与主句的谓语动词和人称保持一致，故本题答案应为B。