do是用在修饰动词的疑问句里,句型为：疑问词+do/does/did+名词+动词原型,例句：what did you eat last night?
am,is,are之类的be动词是用在
1、修饰名词和形容词的疑问句里,句型为：疑问词+am,is,are+名词,例句：when is your birthday?2、现在进行时和过去进行时的疑问句里,例如：what are you doing?
如果讲的不明白,可以继续帮你解答 ^ ^.