I am a student.
am是谓语,在中文中相当于”是”,”做”等动词．
a student是宾语．宾语是谓语后面加的名词性的成分．
有的句子没有宾语．
如：
I walk.我走路．
定语是修饰语,一般单个词的定语是形容词,用来描述物体的具体特征．
比如：
a beautiful woman
beautiful 是定语
还有定语从句,是用一个句子作为修饰语：
the dress that I bought yesterday 我昨天买的裙子
that I bought yesterday就是定语从句．
状语分原因状语,目的状语,时间状语等．
原因状语：
I was late for school because there had been a traffic jam.
because there had been a traffic jam就是原因状语．
目的状语：
I work hard in order to get good grades.我为了拿好成绩而努力学习．
in order to get good grades就是目的状语．
时间状语：
As soon as we got home,the rain stopped.我们一到家,雨就停了．
As soon as we got home就是时间状语．
此外,还有结果状语．顾名思义,就是表结果的．
比如,他学习努力所以考的好．”所以考的好”就是结果状语．
补语是用作补充说明的．
代词有人称代词等,是名词性的,主要有I,you,he,she,it,they,them等等．
冠词就三个：
the,定冠词
a,an,不定冠词．
谓语动词就是指在句子中充当谓语成分的动词．（例子见上）．非谓语动词谓语动词就是指在句子中不充当谓语成分的动词．