以下是引用qiqi_cola在2003-9-23 22:54:00的发言:砖头:p176
Radioactive radon gas emanating from rock such as granite puts inhabitants of houses built on such rock at greater risk of lung cancer the longer the inhabitants are exposed. Protective steps should be taken if radon measurements exceed 4 picocuries per liter; this recommendation is based on 70 years of occupancy by any one person.
If a 65-year-old homeowner concludes from the information above that radon testing for the new home she has purchased will not be necessary,then each of the following,if ture, weakens the homeowner's argument EXCEPT:
A Houses in which the homeowner previously lived were in an area where elevated radon levels have been found.
我觉的这个答案跟题目无关啊。