1. 到底何時(shí)使用did？
did和其它助動(dòng)詞一樣，本身無(wú)意義，自己不能獨(dú)立作謂語(yǔ)，只能和其它主要?jiǎng)釉~一起構(gòu)成謂語(yǔ)，用于構(gòu)成一般過(guò)去時(shí)的否定句和疑問(wèn)句，當(dāng)然也常常用于代替上文中的行為動(dòng)詞的過(guò)去式。如:
I didn't go to school last Sunday. 上周日我沒(méi)上學(xué)。
Did you buy a new pen yesterday? 昨天你買(mǎi)了枝新鋼筆嗎？



2. did身后的動(dòng)詞到底用什么形式？
有的小朋友總不注意did身后的動(dòng)詞用什么形式，在否定句和疑問(wèn)句中，
did身后的動(dòng)詞必須用原形。  “他昨天沒(méi)有在家吃午飯?！?/span>
[誤] He didn't had lunch at home yesterday.
[正] He didn't have lunch at home yesterday.



3. 我能用be動(dòng)詞代替嗎？
不管怎么說(shuō)，含有行為(實(shí)義)動(dòng)詞的一般過(guò)去時(shí)的肯定句變成否定句或疑問(wèn)句時(shí)，不能用be動(dòng)詞，必須用到did！含be動(dòng)詞的句子構(gòu)成否定句或疑問(wèn)句都絕不會(huì)讓did露面！  
例句：They went to the park last week. (改為否定句)
[誤] They weren't go to the park last week.
[正] They didn't go to the park last week.