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.
小学二年级2A英语家庭复习
小学二年级英语单词家庭作业
小学三年级快乐英语单词词组家庭复习
小学二年级英语上学期单词家庭复习
新世纪英语小学二年级unit7作业
小学二年级英语单词句型家庭复习
三年级英语下册第十模块句型和短语家庭作业
新世纪英语小学二年级unit8家庭复习
沪小学二年级英语家庭单词复习
小学二年级英语第一阶段单词家庭复习
小学三年级家庭作业试题
小学二年级英语单词和句子家庭作业
沪教牛津版小学二年级英语单词家庭训练
小学三年级英语下册家庭总复习资料
三年级英语句型和短语家庭作业
小学英语三年级家庭作业题
新世纪英语小学二年级unit8家庭作业
小学三年级英语周末家庭作业
小学三年级分类单词家庭复习
小学二年级英语单词家庭作业
小学三年级英语家庭总复习
小学二年级英语期末单词家庭复习
新世纪英语小学二年级unit3家庭练习
小学二年级牛津英语家庭作业
小学二年级英语单词家庭总复习
牛津小学二年级英语2A句型练习
小学二年级英语家庭摸底题
小学三年级上册英语单词带音标家庭练习
新世纪英语小学二年级unit7家庭练习
小学三年级英语下册短语和重点句型家庭作业
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |