句中有
谓语动词的话就要用do,does，作为
助动词；句中宾语是形容词或名词的话就要is are，作为
系动词。当句子主语是第三人称时，助动词(do)就要用三单形式does，系动词(is,are)就要用is。另外，当句中主语是单数的话，系动词也要用is。
当主语是you的时候，提问也用are还有时态问题。如果是
过去式 那提问的时候也要用过去式。 如he is a boy-----------------Is he a boy? he是三单，所以用is
they are boys.-----------Are they boys? they 是复数，所以用areyou are a teacher----=are you a teacher? you 是
第二人称 用are
he eats meat.---------Does he eat meat? eat是谓语动词，所以要用助动词do，因为he 是三单，所以用does
they eat meat.------Do they eat meat? eat是谓语动词，所以用助动词do，因为they 是复数，所以就不用does，仍旧用do he was a student-----------------was he a student? was 是过去式，提问也用washe ate meat.---------did he eat meat? ate是eat的过去式，提问同did（do的过去式）you were a teacher that moment.---------were you a teacher that moment? 时态一定要先确定好。