There are two main causes of cancer: heredity and environment. We can do nothing to change our heredity, that is, the basic physical characteristics that were passed on to us by our parents. However, we can do a GREat deal to control our environment, which may account for 80-90 %of all cancers.

　　Environmental pollution can be divided into two kinds: personal and impersonal. Personal pollution may be defined roughly as unhealthy habits such as smoking, drinking, and eating the wrong foods. Clearly, with enough will power we can control this personal environment.

　　Impersonal pollution, on the other hand, refers to those things which are beyond our individual control. One example would be industrial pollution, which is very hard to control because of the expense involved. It would be expensive in terms of profits and perhaps jobs. The American automobile industry, for example, resisted the law requiring smog-control devices because it feared the added expense would reduce profits. Nevertheless, some laws protecting the environment have been quite successful in reducing pollution.

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作文地带知识拓展:

• 英语（English）属于印欧语系日耳曼语族西日耳曼语支，最早被中世纪的英国使用，并因其广阔的殖民地而成为世界使用面积最广的语言。英国人的祖先盎格鲁部落是后来迁移到大不列颠岛地区的日耳曼部落之一，称为英格兰。这两个名字都来自波罗地海半岛的Anglia。该语言与弗里斯兰语和下撒克森语密切相关，其词汇受到其他日耳曼语族语言的影响，尤其是北欧语（北日耳曼语），并在很大程度上由拉丁文和法文撰写。

  英语的英文释义：

  English 名词 uk  /ˈɪŋ.ɡlɪʃ/ us  /ˈɪŋ.ɡlɪʃ/

  the language that is spoken in the UK, the US, and in many other countries

  英语

  American/British English

  美式／英式英语

  Do you speak English?

  你会说英语吗？

  English   形容词 adjective   uk  /ˈɪŋ.ɡlɪʃ/ us  /ˈɪŋ.ɡlɪʃ/

  in or relating to the English language

  英语的

  an English teacher

  英语老师

  relating to or from England

  英格兰的;英国的

  English films/food/people

  英国电影／食品／人

  English law

  英格兰法律