句子构成的成分共分为九种：主语，谓语，宾语，表语，定语，状语，补语，同位语和插入语。
一、主语：句子的核心主体，通常位于谓语动词之前，表明一个句子是谁或何种情况所发出执行或是承受的。在写作中常做主语的有名词、代词、主语从句、V-ing、To do五种。
1名词：Computersare now being widely used in almost all fields.
2代词：Weare now living in an information-explosion era.
3主语从句：Whether sports stars should earn a high salaryis still discussed heatedly.
4V-ing:Surfing the Internetoffers a new way for people to relax themselves.
5To do:To protect the environmentis everybody’s business.
二、谓语：描述或阐述主语的情况，由动词来充当，常位于主语之后。
1表状态用系动词：As I see it, movie stars’earning a high salaryisunfair and unjustified.
2表动作用及物或不及物动词：The Internethas revolutionizedpeople’s way of life. Tastediffers.
3表拥有：人或物时用：have has无生命的东西：there be
Peoplehavedifferent views on this question.
There isno absolute agreement on this question.
4情态动词＋动词原形：
In this way, teacherscan never be replacedby computers.
三、宾语：及物动词或介词所指向的对象。在写作中常做宾语的有名词、宾语从句、复合结构、V-ing、To do五种。
1名词作宾语：International tourism promotesthe economic development.
2宾语从句作宾语：Some people holdthat air travel should be restricted.
3复合结构：The advanced medical technology has madeit possible for people to live longer than ever possible before.
4 V-ing: Nobody can avoidbeing influencedby media.
5 To do: Some people wantto work for a big companywhile others chooseto work for a small one.
四、表语：接在系动词后，补充说明主语的情况又称为主语补足语。在写作中常做表语的有名词、形容词、V-ing、To do、从句五种。
1名词：The environmental problem isa serious problemin modern society.
2形容词：Time isfleetingand art islong.
3V-ing: The argument isconvincing.
4To do: A possible solution isto set down effective laws.
5从句：One advantage of computers’utilized in education isthat they can enrich the traditional teaching method to a great extent.
五、定语：修饰名词或类似于名词的词。一般翻译为“……..的”，表示事物性质或状态，分为前置或后置。在写作中常做定语的有形容词、名词、V-ing、To do、从句五种。
1形容词：Taking part-time jobs exertsprofoundimpacts on one’s future career development.
2名词：Generationgap is now a problem we have to face.