连系动词是一个表示谓语关系的动词,它后面必须接表语（通常为名词或形容词）.
Be是最基本的连系动词.如：
My idea is to go there right away.
He is a basketball player.
常用的连系动词还有appear,become,get,look,remain,seem等.如：
The leaves become yellow when it is autumn.
His face got red when he heard the news.
表知觉和感觉的动词也可以是连系动词,有feel,taste,smell,sound等.如：
