吉林省四平市2014高考英语阅读理解巩固全程训练（12）及答案
【广东省高三考前冲刺卷(六)】
By analyzing the DNA of the world’s oldest people，Boston University scientists said they have discovered a genetic signature(特征)of longevity.They expect soon to offer a test that could let people learn whether they can live to a very old age.
The researchers said they had no plans to patent the technique or profit from it.Instead，they expect to make a free test available on the Internet later this month to promote longevity research.
The test might show something that people wouldn’t like to know，the BU scientists warned.Genetic testing often reveals attractive but incomplete information，and it is sometimes difficult to know how to respond.People with genes for extreme longevity could face a series of difficult decisions about their careers，retirement savings，insurance coverage，medical treatments and marriages in old age.
Scientists have long sought to crack the genetic code of healthy aging.On average，people in developed countries can expect to live between 80 and 85 years，largely as a result of improvements in diet and public health.But the oldest of the old—the “wellderly”—live two to three decades longer，often free of mental and physical diseases.
The free test will be available through a public website maintained by the New England Centenarian Study.But to
