连系动词是一个表示不完全谓语关系的动词,它必须后接表语,表语通常是名词和形容词,它既没有被动语态,也没有进行时态.如：
He was a painter,but a very bad one.
I am very hungry and tired.
最基本的连系动词是be,如：
He is strong.
He is a strong man.
The man is here.
Mary is in the house.
We are of the same opinion.
That is out of the questiion.
That is why I like the movie "The Sound of Music" best.
The problem is to find (finding) the right house.
常见的连系动词还有appear、become、get、look、remain和seem.
表示感觉和知觉的动词,也是连系动词,如：feel、taste、smell、sound等.
The rose smells sweet.
The milk tastes sour.
有些和形容词连用的动词,也可以是连系动词,如：blow、break、blush、grow、fall、prove、stand、turn、wax等.
be和及物动词的过去分词一起构成被动语态的时候,be作为助动词出现,而不是连系动词,没有实际意义.如：
The thief was caught in the parking lot.
The child is crying because he has been stung by a bee.
希望我能帮助你解疑释惑.