be动词是动词,在句子中做谓语.助动词是起辅助作用的,不可以直接做谓语.例如：I am a student.疑问句：Are you a student?be动词的句子改为疑问句,将be动词提到句首.I like apples.我喜欢苹果.Do you like apples?Do ...