isn't it(she/he)前面的动词是原形还是加什么形式
问题描述：
isn't it(she/he)前面的动词是原形还是加什么形式
mr.lee____(give)us a talk on the history of china tomorrow,isn't he?they____(fly)to the uk,didn't he?
答
flew to the uk
看V.是过去或是未来决定