这句话为什么用did 不用doI don't go to school any more, but if I did , I would read the material before class请大家说一下为什么用did不用do呢

这句话为什么用did 不用doI don't go to school any more, but if I did , I would read the material before class请大家说一下为什么用did不用do呢 How much did the computer cost ben?这句话中为什么要用did不用do? 英语语法,hardly did i think it impossible这句话为什么有did还用think而不用thought,还有it后面为什么不用is,谢谢 这句话为什么did不用问号?The manager never laughed; neither did she become angry. 这句话的语法不理解Did the students have any problems in their studies?为什么不用study 而用studies? I have not received my pay yet.这句话为什么要用have,为什么不用don't? did you ever see such a 那为什么这句话不用现在完成时呢? I don't know what to doI don't know what I do这两句话意思一样吗? 都是宾语从句? I won't buy that I don't need it请问这句话中的will为什么要用过去式,如果不用will用don't 请问For her to steal my heart away when she don't care 这句话为什么用“don't,而不用doesn't? 为什么要用did而不用do, which books did you by 为什么用did 不用were How did you get here?为什么用did不用were? so did the flowers give you some ideas?这句话为什么不用any而用some,疑问句不是应该用any吗? As soom sa this was done,they cooke a meal over an open fire.请问这句话中,为什么要用was done?而不用did? I could not hear the actors为什么用could不用did?为什么不用did not 【急求】在什么情况下疑问句中要用助动词do?什么时候要用do/did/dose?什么时候不用?就像what did you do? 和 what happened? 为什么第二句话不用what did happened? Did you < >a bike before 为什么不要用过去试,Dont ( ) too much.为什么不用过去试?plase ( )evey day.用过去试还 是原试,