Nobody has never been to Mars, haven't they?本来有nobody在句首,表否定,那么该句是have they?但是句中又出现了never,同样是表否定的一个词,那么整一句话就变成了双否表示肯定,前面句子是肯定,那么反义疑问句就应该是否定的,所以答案是haven't they.希望有帮助
have they?请及时采纳,不懂继续问( 天天在线 )(*^__^*) 祝学习进步! 谢谢!