Did he have a picnic last weekend?why?為什么用did？什么時(shí)候用was開(kāi)頭？過(guò)去式啊，did是助動(dòng)詞，was是系動(dòng)詞， did提問(wèn)的是過(guò)去發(fā)生的動(dòng)作，接的是動(dòng)詞，如 Did you go(動(dòng)詞原形) to school yesterday? was直接提問(wèn)的是名詞、形容詞等，如： Was he happy yesterday? 當(dāng)然，如果是過(guò)去進(jìn)行時(shí)或者過(guò)去將來(lái)時(shí)會(huì)用was，如： Was he sleeping when you came back yeasterday? Was he going to sing if he felt happy?你可以把句子還原成肯定句，was變成肯定句，也存在，did變成肯定句就不存在了，而是用動(dòng)詞的過(guò)去式代替。比如此題，變?yōu)榭隙ň涫牵?He had a picnic last weekend. 而不是： He was have a picnic last weekend. 當(dāng)然，如果說(shuō)： He was going to have a picnic last weekend. 這種說(shuō)法也可以，過(guò)去將來(lái)時(shí)。不過(guò)時(shí)間條件上應(yīng)該更明顯些!