Cancer and Environment
提纲
1．癌症的两个起因。
2．造成癌症的环境原因。
3．非个人原因造成的环境污染。
There are two main causes for cancer: heredity and environment. We can do nothing to change our heredity, that is, the basic physical characteristics that arepassed on to us by our parents. However, we can do a great deal to control our environment, which may account for eighty to ninety percent of a
