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  3. Lonely people，it seems，are at greater risk than the gregarious of developing illnesses associated with chronic inflammation，such

Lonely people，it seems，are at greater risk than the gregarious of developing illnesses associated with chronic inflammation，such

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问题    Lonely people，it seems，are at greater risk than the gregarious of developing illnesses associated with chronic inflammation，such as heart disease and certain cancers．A paper published last year in the Public Library of Science，Medicine，shows the effect on mortality of loneliness is comparable with that of smoking and drinking after examining the results of 148 previous studies and controlled for factors such as age and pre-existing illness．
    Steven Cole of the University of California，Los Angeles，thinks he may know why this is so．He told the American Association for the Advancement of Science meeting in Washington，D．C．，about his work studying the expression of genes in lonely people．Dr．Cole harvested samples of white blood cells from both lonely and gregarious people．He then analysed the activity of their genes，as measured by the production of a substance called messenger RNA．This molecule carries instructions from the genes telling a cell which proteins to make．The level of messenger RNA from most genes was the same in both types of people．There were several dozen genes，however，that were less active in the lonely，and several dozen others that were more active．Moreover，both the less active and the more active gene types came from a small number of functional groups．
    Broadly speaking，the genes less active in the lonely were those involved in staving off viral infections．Those that were more active were involved in protecting against bacteria．Dr．Cole suspects this could help explain not only why the lonely are iller，but how，in evolutionary terms，this odd state of affairs has come about．
  The crucial bit of the puzzle is that viruses have to be caught from another infected individual and they aye usually species-specific．Bacteria，in contrast，often just lurk in the environment，and may thrive on many hosts．The gregarious are therefore at greater risk than the lonely of catching viruses，and Dr．Cole thus suggests that past evolution has created a mechanism which causes white cells to respond appropriately．Conversely，the lonely are better off ramping up their protection against bacterial infection，which is a bigger relative risk to them．
    What Dr．Cole seems to have revealed，then，is a mechanism by which social environment reaches inside a person’s body and tweaks its genome so that it responds appropriately．It is not that the lonely and the gregarious are genetically different from each other．Rather，their genes are regulated differently，according to how sociable an individual is．Dr．Cole thinks this regulation is part of a wider mechanism that tunes individuals to the circumstances they find themselves in．
What can we know about viruses and bacteria from the fourth paragraph?
选项 A、Viruses often remain hidden in the environment．
B、Bacteria are passed to other people by the infected individual．
C、The lonely people can catch viruses more easily．
D、Viruses pose a greater threat to the gregarious than bacteria．
答案D
解析 细节题。根据题干信息定位到第四段。根据本段前三句可知，病毒只有通过另一个已被感染此病毒的人才能传染给某个人，并且病毒通常有其一对一的特殊宿主。相比之下，细菌经常潜伏在周围环境中，并且宿主众多。所以爱交际的人比孤独的人更易感染病毒。由此可见，病毒较之细菌对爱交际的人的威胁更大，故D项为正确答案。原文提到经常潜伏在周围环境中的是细菌，而不是病毒，故A项错误。B项描述的是病毒的传染方式。C项与原文中的The gregarious are therefore at greater risk than the lonely of catching viruses描述矛盾。故本题选D。
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