关键词作文就是根据作文题目及所给的关键词，在正确理解词义的基础上，依据自己的知识，进行联想和组织文字，写出既能合理利用关键词，又能表达思想的文章。关键词作文可适用于各种文体。如：
Directions: For this part, you are allowed 30 minutes to write a composition about “ The Earth” in three paragraphs. You are given some key words and are required to develop its ideas. Write about 120 words for your essay. Remember to write clearly on the Answer Sheet.
                                                                                    The Earth
Key Words: earth, planet, be fit for, human being, air, water, damage, pollute, use up, resource, measures, protect, importance, environmental, ways, make use of, waste, save

我们在写关键词作文时应按下列步骤进行：
1．审题。相对于段首句作文来说，审题对于关键词作文更为重要。由于关键词作文是带题目的，所以拿到作文后一定要认真审题，仔细琢磨题目的含义，弄清题目规定的内容及各段的主题，确定写作题材。
2．仔细阅读关键词。关键词作文一般来说要难于段首句作文。而对于所给的关键词，考生往往感到茫然，不知如何动笔。遇到这种情况，要仔细阅读关键词，因为所给的关键词通常是分段落的，并且按照一定的逻辑关系排列。它们不仅规定了思路，而且在一定程度上还提供了语言素材，考生可根据所给的关键词进行联想，勾画出短文的轮廓。
3．草拟各段的主题句。明确了全文各段的主题，只是对如何写好这篇文章有了初步的设想。要写好文章，还有关键性的一步，这就是写出各段的主题句。主题句是作者思维的起点、扣题的准绳、阐述的对象。有了主题句，作者就可以围绕主题句进行扩展，不会偏题。写主题句时要注意以下几个问题：
(1) 完整性。完整性是指主题句必须是一个意义完整、主谓成分俱全的句子。
(2) 清晰性。清晰性是指主题句的含义要清晰明了，使人容易分清，不要含糊其词，使人感到模棱两可。
(3) 具体性。具体性是指主题句要明确具体，内涵集中，所指单一，易于段落的扩展。
(4) 正确性。正确性是指主题句用词要能确切地表达本段所写的内容，语言要精炼、生动、清晰。
4．段落写作。考生在用关键词写作文时，应尽量将所给的词都用上，并力求把每个关键词都用得准确、形象、恰到好处。写作时，要特别注意句子的结构，句子与句子之间的衔接，以及段落与段落之间的转折和连接。
参考范文:
The Earth
The earth is now the only planet that is fit for human beings. The air around it forms a protection that prevents the earth from getting neither too hot nor too cold. The water, the trees, and other things on the earth are essential for man.
Unfortunately, the earth we live on is severely damaged because of the high civilization. Modern factories provide us with best commodities at the cost of polluting the environment. To meet the needs of the ever-increasing population, we are using up natural resources.
Measures must be taken to protect the earth. First, we should teach people the importance of the environmental protection. Second, we should make machines that will use less energy and will do the minimum damage to the environment. Third, we must figure out ways to make use of waste to save natural resources.
练习题 1：
Directions: Write a composition on the topic “Constant Dropping Wears the Stone”. Your composition should be based on the following key words. You are expected to include all of them. Remember to write clearly and present your own ideas.
Key Words: coupled with, perseverance, incredible, formidable, pursuit, destined to, a case in point
练习题 2：
Directions: For this part, you are allowed 30 minutes to write a composition entitled “Unemployment”. Write no less than 120 words. Be sure to include the following words and phrases.
Key Words: economic, reform, laid-off, workers, problem, inevitable, system, temporary, intelligence, iron bowl, knowledge
练习题 3：
Directions: For this part, you are allowed 30 minutes to write a composition on the topic “Computers”. Your composition should be based on the following key words and expressions, and it should be no less than 120 words long.
Key Words and Expressions : many changes, development, scientific research and engineering, too complicated, program, automatically, facts, take over, nothing but machines, take the place of