系动词亦称联系动词（Link Verb）,作为系动词,它本身有词义,但不能单独用作谓语,后边必须跟表语（亦称补语）,构成系表结构说明主语的状况、性质、特征等情况.
说明：
有些系动词又是实义动词,该动词表达实义时,有词义,可单独作谓语,例如：
He fell ill yesterday.
他昨天病了.（fell是系动词,后跟补足语,说明主语情况.）
He fell off the ladder.
他从梯子上摔下来.fell是实义动词,单独作谓语.
1）状态系动词
用来表示主语状态,只有be一词,例如：
He is a teacher. 他是一名教师.（is与补足语一起说明主语的身份.）
2）持续系动词
用来表示主语继续或保持一种状况或态度,主要有keep, rest, remain, stay, lie, stand, 例如：
He always kept silent at meeting. 他开会时总保持沉默.
This matter rests a mystery. 此事仍是一个谜.
3）表像系动词
用来表示"看起来像"这一概念,主要有seem, appear, look, 例如：
He looks tired. 他看起来很累.
He seems (to be) very sad. 他看起来很伤心.
4）感官系动词
感官系动词主要有feel, smell, sound, taste, 例如：
This kind of cloth feels very soft.
这种布手感很软.
This flower smells very sweet.
这朵花闻起来很香.
5）变化系动词
这些系动词表示主语变成什么样,变化系动词主要有become, grow, turn, fall, get, go, come, run.
例如：
He became mad after that. 自那之后,他疯了.
She grew rich within a short time. 她没多长时间就富了.
6）终止系动词
表示主语已终止动作,主要有prove, trun out, 表达"证实","变成"之意,例如：
The rumor proved false. 这谣言证实有假.
The search proved difficult. 搜查证实很难.
His plan turned out a success. 他的计划终于成功了.
英语系动词的分类
系动词词义不完整,在句中不能单独使用（除省略句外）,后面必须接有表语,系动词和表语一起构成合成谓语.
一、系动词的分类：
常见的系动词大致可分为三类.
第一类：表示特征或状态的,有be, look, feel, seem, appear, smell, taste, sound, turn, out（结果是、证明是）等.
You”ll be all right soon.
You don”t look very well.
I feel rather cold.
He seems to be ill.
It appears that he is unhappy.
The roses smell sweet.
The mixture tasted horrible.
How sweet the music sounds!
The day turned out (to be) a fine one.
第二类：表示从一种状态到另一种状态的变化,有become, get, grow, turn, fall, go, come, run等.
He became a world-famous scientist.
It is getting warmer and warmer.
It grew dark.
The food has turned bad.
Yesterday he suddenly fell ill.
Mary”s face went red.
His dream has come true.
The boy”s blood ran cold.
第三类：表示保持状态的,有keep, remain, continue等.
Keep quiet, children!
The weather continued fine for a long time.
It remains to be proved.
系动词后的表语可以是名词、代词、数词、形容词、分词、动名词、不定式、副词、介词短语、词组、从句,系动词be可用于上述所有情况.如：
The pepople are the real heroes.（名词）
That”s something we have always to keep in mind.（代词）
She is often the first to come here.（数词）
She is pretty and wise.（形容词）
The news was surprising.（分词）
His job is teaching English.（动名词）
The only method is to give the child more help.（不定式）
I must be off now.（副词）
The bridge is under construction.（介词短语）
That would be a great weight off my mind.（词组）
This is why he was late.（从句）
二、系动词的使用特点：
1. 所有的系动词都可接形容词作表语,此处略举数例.
Our future will be beautiful.
She looks unhappy today.
Do you feel cold?
You seem/appear ill.
The food tastes delicious.
The weather is turning/ growing/ becoming/ getting cold.
He often went hungry.
2. 能用名词作表语的系动词有：be, become, turn sound, remain, seem等.
He was a postman six years ago.
He has become a famous doctor.
He turned traiter to his country.
That sounds a good idea.
He remains an ordinary worker.
He seems a stranger to me.
3. 能用不定式作表语的系动词有：appear, seem, get, prove, remain, turn out等.
She appears/ seems to be very young.
He appears/ seems to have caught cold.
They got to be friends.
The meeting turned out to be successful.
The theory proved to be right.
Much remains to be done.
4. 能接从句的有：be, seem, appear, sound, look等.
That”s why he fell ill.
My idea is that we should help him.
It seems/ appears to me that something is wrong.
It sounds to me as if someone were trying to get into the house.
Your voice sounds as if you had a cold.
It looks as if it is going to rain.
5. 能接介词短语的有：be, feel, look, sound, taste, remain等.
be是特别活跃的系动词,其后可接很多介词短语作表语.
He is at home/ in the library/ on the way home/ on holiday.
The police are after him.
He is at work on a new invention.
He found the girl was in tears.
They are on duty/ on strike/ on leave.
The road is under repair.
其他系动词能和介词搭配的范围很小.如：
It feels like a rain.
It looks like a rain.
It sounds like a train going under my room.
It tastes of apples.（这有苹果的味道.）
The concert remains in my memory.
6. 能接分词的系动词有：be, become, get, grow, seem, appear等.
His report was surpring/ disappointing/ delighting/ moving/ astonishing…
The boy was moved/ delighted/ surprised/ disappointed/ astonished.
He has become/ got/ grown/ interested in modern physics.
He seems/ appears drunk.
系动词后还可接代词、数词、动名词、副词及其词组,基本都是be的用法.其他系动词几乎不能这样用或很少这样用,这里就不再赘述了.