When did it start?About ______ago.怎么填?

When did it start?About ______ago.怎么填? When did it start?About ______ ago. When did it start? when did it start? 解释 It's raining .when did it start? -It's raining!When did it start? 是when did it started还是when did it start? When did it start?为什么did用过去式? when did you start doing it?请翻译 When did you start learning English怎么回答 When did you start playing table tennis? 怎么回答 自学英语,When did it start raining.一个句子里的start doing是怎么回事?