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 stilldiscussed heatedly.
4 V-ing：Surfing the Internetoffers a new way for people to relaxthemselves.
5 To 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 andunjustified.
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。Peoplehavedifferentviews on this question.There isno absolute agreement on this question.
4情态动词+动词原形：In thisway, 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 forpeople 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 otherschooseto 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 modernsociety.
2形容词：Time isfleetingand art islong.
3 V-ing：The argument isconvincing.
4 To do：A possible solution isto set down effective laws.
5从句：One advantage of computers'utilized in education isthat theycan 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 futurecareer development.
2名词：Generationgap is now a problem we have to face.
名词做定语(名词修饰名词重要原则：第一个名词一般用单数以下为雅思写作常用名词修饰名词词组)
Informationtechnology、Information center、Credit card、Generationgap、Beauty contest、Communication skills、Information age、Knowledge economy、Peace talks、Serviceindustry、Water scarcity、Survival skills、Press conference、Safety standard、Life insurance、Weatherforecast、Reception desk、Coffee break、Body guard、Heart attack、Departmentstore、Stock market、Office building、Science fiction
3 V-ing：Clearly, we are now living in anupdatingsociety and the worldis now witnessing somebreath-takingchanges.
4 To do：Studying abroad provides students with a good opportunitytoexperience a totally different culture.
5定语从句：That is a good bookwhich is opened with expectation andclosed with profit.
六、状语：修饰动词、形容词、副词或整句的词或句。按照功能分十一种：时间、地点、原因、目的、结果、方式、条件、让步、比较、伴随、评注。在写作中常做状语的有副词、状语从句、状语从句省略结构、To do、V-ing、V-ed
从句六种：
1副词：Honestly, I cannot give a yes-no answer to this question.
2状语从句：Where there is an open mind, there will always be frontier.
3状语从句省略结构：If so, the conclusion still remains questionable.
4 To do：To solve this problem, people think up various solutions.
5 V-ing：Technology is developing by leaps and bounds,making itpossible for people to live better than ever before.
6 V-ed：Encouraged to do so, children will experience betterdevelopment.
七、补语：主语补足语(补充说明主语的情况，又称表语)、宾语补足语(补充说明宾语的情况)在写作中常做宾语补足语的有形容词和To do 两种。
1形容词：Many people find this experienceawful.
2 To do：Advertisements often urge peopleto buy goods they do not need.
八、同位语：句子中的两种成份表达同一种概念，即A=B称之为同位语。在写作中常做同位语的有名词和从句两种。
1名词：We should learn from the past,the mirror of the present andthe hope of the future.
2从句：University students should bear total expenses for theirtuition on the generalizationthat university students usually earn much morethan people without a degree.
九、插入语：插入语是说话者对所表达意思的补充、强调、解释或者说话的态度，其位置灵活，常常用逗号或破折号与其它成分隔开，并且在语法上不影响其他成分。书面表达要求语言连贯、地道，恰当使用插入语，可以给文章增色不少。在写作中常用的插入语如下：
Indeed的确，Surely无疑，However然而，Obviously显然，Frankly坦率地说，Naturally自然，Luckily(或happily)for somebody算某人幸运，Fortunately/Luckily幸好，Honestly真的，Briefly简单地说，Strange to say说也奇怪，Needlessto say不用说，Mostimportant of all最为重要是，Worse still更糟糕的是，Ina few words(或in sum，in short)简而言之，Inotherwords换句话说。
