公共英语PETS考试精选80篇背诵范文含翻译(六十)
来源:优易学  2011-5-6 18:57:56   【优易学:中国教育考试门户网】   资料下载   外语书店

Colds and Age 
  A critical factor that plays a part  in susceptibility to colds is age. A study done by the University of Michigan School of Public Health revealed particulars that seem to hold true for the general population. 
  Infants are the most cold ridden group, averaging more than six colds in their first years. Boys have more colds than girls up to age three. After the age of three, girls are more susceptible than boys, and teenage girls average three colds a year to boys’ two. The general incidence of colds continues to decline into maturity. Elderly people who are in good health have as few as one or two colds annually. One exception is found among people in their twenties, especially women, who show a rise in cold infections, because people in this age group are most likely to have young children.  
  Adults who delay having children until their thirties and forties experience the same sudden increase in cold infections. The study also found that economics plays an important role. As income increases, the frequency at which colds are reported in the family decreases. Families with the lowest income suffer about a third more colds than families at the upper end.
   Lower income  generally forces people to live  in more cramped quarters than those typically occupied by wealthier people, and crowding increases the opportunities for the cold virus to travel from person to person. Low income  may also adversely  influence diet. 
  The degree towhich poor nutrition affects susceptibility to colds is not yet clearly established, but an inadequate diet is suspected of lowering resistance generally.

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