only this morning did i I hear the sad news,为什么要加DID

I would rather they did not hear the news.这句话是虚拟用法 为什么要用过去式. i did not hear you because i am listen tothe news on the rad who cleaned the room this morning?I did里面为什么不能用cleaned? not until last week ___the sad news A did i know B did i kne Did you miss the bus this morning? Yes I. missed the bus中文意思 提示:i did not eat breakfast this morning I (did some shopping ) this morning. 括号部分提问 Where did you go this morning?--- I went to the shopping mal -What did you do this morning?-I went to the library,_some m I could not hear the actors为什么用could不用did? Tom did not eat anything this morning?A so did i B neither d I did some exercise this morning .(改疑问句,否定句,把did some exerci