am is are 举例1、I am a boy./I am a teacher.(am用于第一人称也就是我)2、She is a nurse./He is a driver./It is a dog (is 用于第三人称单数情况 he. she .it和其它的三单形式,我的书包,等)3.You are a girl./They are friends./The apples are on the desk.(are用于第二人称,你和复数情况。)