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.
癌症有两个主要原因：遗传和环境。我们不能改变我们的遗传，也就是说，我们父母遗传给我们的基本身体特征。但是，我们可以做很多事情来控制我们的环境，这可能占所有癌症的80-90%。
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.
环境污染可以分为两种：个人的和非个人的。个人污染可以大致定义为不健康的习惯，如吸烟、饮酒和吃错食物。显然，只要有足够的意志力，我们就能控制这个个人环境。
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.
另一方面，非个人的污染指的是那些超出我们个人控制的东西。一个例子是工业污染，由于所涉及的费用很难控制。从利润和工作岗位来看，这将是昂贵的。例如，美国汽车工业抵制了要求使用烟雾控制装置的法律，因为它担心增加的费用会减少利润。尽管如此，一些保护环境的法律在减少污染方面还是相当成功的