The teacher and the student are in the class-room这个句子正确吗?如果错误,错在哪里,请写下来,

这个句子是正确的,Be动词用are是对的,主语是这个老师和这个同学.但比如：A signer and artiest is in the class-room.这时主语是指一个人（既是歌手又是艺术家）A signer and a artiest are in the class-room.这时...