词类和句子成分的关系：
1．主语：是句子要说明的人和物,是句子的主体,一般放在句首.名词、代词常在句中作主语.此外,动名词、动词不定式、主语从句也可作主语.例如：
1)Mr.Chen is a greadt scientist.(名词作主语)
2)He reads newspapers every day.(代词作主)
3)Smoking is harmful to the health.(动名词作主语)
4)To swim in Kuming Lake is a great pleasure.(动词不定式作主语)
5)What we shall do next is not yet decided.(主语从句作主语)
2．谓语：说明主语的动作和状态.动词在句中作谓语,一般放在主语之后.例如：
1)The new term begins on September 1st .(行为动词作谓语)
2)She seems tired.(连系动词作谓语)
3)He has gone to Beijing.(行为动词作谓语)
3．宾语：及物动词涉及的人或物称为动词宾语.宾语一般放在及物动词（或相当于及物动词的短语）后.介词后的名词或代词称为介词宾语.名词、代词在句中常作宾语.此外,动词不定式、动名词和从句也可作宾语.例如：
1)Wang Ling lent me a novel.(代词me作间接宾语；名词a novel作直接宾语)
2)The medicine is good for a cough.( 名词a cough作介词宾语)
3)My little sister always likes to ask questions.(不定式to ask questions作动词likes 的宾语)
4)His brother is good at playing chess.(动词名词playing chess作介词宾语)
5)Would you mind coming earlier tomorrow?(coming作动词宾语)
4．宾语补足语（复合宾语的第二部分）：在宾语后补充说明宾语的动作、状态、特征的成分称为宾补.名词、形容词、动词不定式和动名词可作宾补.（见前面简单句的五种基本句型五）
5．表语：在连系动词后用来说明主语的身份、状态或特征的成分是表语.可作表语的有：名词、代词、形容词、介词短语、不定式、动名词以及表语从句.（参见简单句的五种基本句型三）
1)Wang Lin’s father is a doctor.(名词a doctor作表语,说明主语的身份是doctor)
2)He is from America.（介词短语from America作表语,说明主语的特征是“来自美国“）
3)The baby is asleep.(形容词asleep作表语,说明主语的状态是“睡着的”)
4)His work is teaching English.(动名词短语teaching English作表语,说明主语特征是“教英语”)
5)This is why he was late for school(表语从句why he was late for school作表语.)
6．定语：用来修饰名词或代词的成分是定语.单词作定语通常放在它所修饰的词前；但修饰复合不定代词（nothing,anything,everything,something ,somebody ,anybody,…..）时,则放在这些不定代词之后.短语和从句作定语时,也放在被修饰词之后.形容词、名词、代词、数词、副词、介词短语、动词不定式、现在分词、过去分词和定语从句等都可作定语.
1)He is reading an interesting book.(形容词interesting作定语,修饰名词book)
2)I have something important to tell you.(形容词important以及不定式to tell you作定语,修饰不定代词something)
3)There are few women workers in the factory.(形容词few 以及名词women作定语修饰名词workers)
4)The oil workers here come from Daqing.(名词oil以及副词here作定语修饰名词workers)
5)We have got ten desks in the room.(数词ten修饰名词desks)
6)Yesterday the scientist made a report on modern science.（介词短语on modern science作定语修饰名词report.）
7)The girl playing the piano is my younger sister.(现在分词短语playing the piano作定语修饰名词girl)
8)This is the new dictionary which I bought yesterday.(定语从句which I bought yesterday作定语修饰名词dictionary)
7．状语：修饰动词、形容词、副词或全句的成分是状语.修饰形容词的状语通常放在它所修饰的词之前,修饰动词的状语通常放在动词后.但有些副词（如：often ,always ,usually等作状语放在事义动词之前,be /助/情之后）.副词、介词短语、名词词组、动词不定式、分词短语和状语从句都可以作状语.
1)He knows how to learn English well.(副词well作状语,修饰动词learn)
2)My parents often tell us about their hard life in the past.(副词often作状语,修饰动词tell)
3)Her mother usually goes out to do some shopping on Sundays.(副词usually以及介词短语on Sundays作状语,修饰动词goes)
4)He will leave for Shanghai the day after tomorrow.(名词词组the day after tomorrow作状语,修饰动词will leave)
5)He came here to see you.(动词不定式to see you作目的状语,
6)He sat there reading a novel (现在分词短语reading a novel作状语修饰动词sat)
7)If I have some free time,I will study German.(条件状语从句If I have some free time作状语)