跑题：在谈论某个话题时，突然转换到与原话题无关的内容。
离题(get off the subject), 此释义来源于网络辞典。
离题
Please can we get off the subject of dieting?
我们别再谈论节食这个话题行吗？
Lett's get off the subject of work! Let's talk about something pleasant!
我们别谈工作了！让我们谈些愉快的事情吧！ ！
I think you are getting off the subject. Could we get back to the main point, please?
我觉得你跑题了。 我们能不能回到主题上来?。