第四、同位语从句
      
Eg: It is an undeniable fact that environmental pollution becomes increasingly serious.
      
环境污染变得越来越严重是不可否认的事实。
      
Eg: No one can deny the basic fact that it is impossible for average workers to master those high-technology skills easily.
      
没有人能否认这一基本事实：对于一般工人来讲，轻松掌握这些技术是不可能的。

第五、主语从句
      
Eg: What has caught our attention is /It is noticeable that the environment in both the rural and urban areas is deteriorating.
      
值得注意的是农村和城市的生态环境都在不断恶化。
      
Eg: It is universally acknowledged that environmental pollution becomes one of the most serious problems in China or even the world as a whole. 众所周知，环境污染问题是中国乃至
世界面临的最为严重的问题之一。

第六、强调句。It is + 被强调的内容 + that
      
Eg: It is cars and factories that release a great deal of gases, polluting the environment.
      
汽车和工厂排放大量的废气，使得环境被污染。

第七、倒装句
      
Eg: Only if the government will take some appropriate measures, will this intractable problem be tackled.
      
只有政府采取适当的措施，这个棘手的问题才能被解决。

第八、被动语态
      
Eg: Every means should be tried to protect the environment on which people live.
      
人们应竭尽全力来保护我们赖以生存的环境。

第九、分词结构。包括现在分词和过去分词。
      
Eg: Tourism, which is a rising industry, has become the major source of economy, playing crucial role in many Asian countries.
      
旅游业是一个新兴的行业，它成为经济的主要来源， 在很多东南亚国家起着尤为重要的作用。
     
Eg: To be more specific, government should stage some relevant laws or regulations to severely punish the factory producing a great number of pollutants and the people littering or spitting deliberately.
      
具体来说，政府应该出台相关法律法规对制造大量污染物的工厂及故意乱扔垃圾随地吐痰的人进行严惩。

第十、插入语
      
一种独立成分，与句子的其它成分一般没有语法上的关系，大都是对一句话作一些附加说明或解释。它通常由一个词、一个短语或一个句子构成，位置较为灵活，可置于句首、句中或句末，一般用逗号
或破折号与句子隔开。
      
Eg: Computer, an indispensable part in our life, has brought us great conveniences.
      
电脑，我们生活中必不可少的一部分，给我们带来了极大的方便。
      
Eg: College students, lacking social experience, are easily cheated.
      
大学生，没有社会经验，容易上当受骗。