主语：句子陈述的对象，说明是谁或什么，或执行句子的行为或动作的主体。
①My school is not far from my house.
②To do such a job needs more knowledge.
谓语：对主语动作或状态的陈述或说明,指出“做什么”、“是什么”或“怎么样”。
①It is used by travelers and business people all over the world.
②I made your birthday cake last night
宾语：一个动作（动词）的接受者。
①He didn't say anything.
②They sent the injured to hospital.
表语：用来说明主语的身份、性质、品性、特征和状态的成分。
①That remains a puzzle to me.
②The sun is up.
定语：用来修饰、限定、说明名词或代词的品质与特征的成分。
①In science, a theory is a reasonable explanation of observed events.
②Possible solutions to the problem are formulated.
状语：谓语里的另一个附加成分,从情况,时间,处所,方式,条件,对象,肯定,否定,范围和程度等方面对谓语中心进行修饰或限制。
①In a way,any hypothesis is a leap into the unknown.
②It extends the scientist's thinking beyond the known facts.
主语补足语：被动语态中的宾语补足语。
①The dog is called Karl.
②The door was painted white.
宾语补足语：某些及物动词的宾语后面还需要有一个补足语，意思才完整，宾语和它的补足语构成复合宾语。
①He proved that theory very important.
②I'd prefer you to leave him alone.
插入语：在一个句子中间插入的一个成分,不作句子的何种成分,也不和句子的何种成分发生结构关系,同时既不起连接作用,也不表示语气。
①One advantage of his icebox, Moore explained, was something.
②The success of the Colorado beetle in infesting potatoes, for example, seems to be correlated with its high tolerance to alkaloids.
连接词：连接短语或子句的句子成分。
①That is, they become diseased and die.
②The baby boomers began streaming into the first grade by the mid-1940's and became a flood by 1950.
同位语：对另一个名词或代词进行修饰，限定或说明的名词或其它形式。
①A new household convenience, the icebox, a precursor of the modern refrigerator, had been invented.
②Most of them range in size from $5,000 to $12,500, a welcome sum to many young practitioners.
系动词：本身有词义，但不能单独用作谓语，后边必须跟表语，构成系表结构说明主语的状况、性质、特征等情况。
①Thatis air wrung dry of moisture.
②There seem to have been several periods within the last tens of thousands of years.
形式主语：形式主语是动词不定式的一种,它也是逻辑主语, 可以把它归类到逻辑主语的第一种(不定式的逻辑主语) 用作宾语的不定式，用作目的状语，用作结果状语的不定式都是属于不定式的大概念里面的。
①It is no use reasoning with him.
② It was pretty hard for him to bring up the child on his own.
形式宾语：形式宾语是动词不定式的一种,它也是逻辑宾语, 可以把它归类到逻辑宾语的第一种(不定式的逻辑宾语) 用作主语的不定式，用作目的状语，用作结果状语的不定式都是属于不定式的大概念里面的。
①I find it difficult to talk to you.
②I think it intresesting to dance.
间接宾语：当看到句子中有两个宾语时，其中指物或指事的就是直接宾语，指人（或动物）的就是间接宾语。（不能按宾语离动词的远近来判别）
①I teach him English.
②I wrote my father a letter yesterday.
连接词/标志词：连接词是连接单词、短语或子句的词语, 不能独立充当句子成分。
①Air and water are indispensable to me.
②You may come if you want to.