一变：肯定句变为否定句

　　【技巧1】当句中含有情态动词或助动词could，would，should等时，可直接在其后面加not构成否定句。例如：

　　I could get you a concert ticket.→Icould not/couldn‘t get you a concert ticket.

　　【技巧2】当句中含有系动词was，were时，可直接在其后加not构成否定句。例如：

　　I was on the Internet when you called me.→I wasnot/wasn’t on the Internet when you called me.

　　【技巧3】当句中谓语是除情态动词、助动词、系动词was，were以外的动词时，在该动词之前加didnot/didn‘t，动词还原，构成否定句。例如：

　　The famous singer sang some Chinese songs.→The famous singer did not/didn’t sing any Chinese songs.

　　二变：陈述句变为一般疑问句

　　【技巧1】移动词语的位置。将was，were，could，would，should等移到句首。例如：

　　He could pack his things himself.→Could he pack his things himself?

　　【技巧2】添加助动词did。谓语是除情态动词、助动词、系动词was，were以外的动词时，在主语之前加did，动词还原。例如：

　　Mr Li looked very old.→Did Mr Li look very old?

　　三变：陈述句变为特殊疑问句

　　【技巧1】确定疑问词：人who/whom，物what，地点where，时间when/whattime，原因why，频率how often，长度how long，距离how far等等。例如：

　　They gave the concert last night.→When did they give the concert?

　　【技巧2】辨认结构形式：疑问词+情态动词/助动词/was/were/did+主语+...?例如：

　　The accident happened near the station.→Where did the accident happen