2008年12月20日大学英语六级A卷真题满分答案

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Part I writing (30 minutes)

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Supersize surprise 本文来自

1. Not enough sleep 本文来自

Although getting figures is difficult, it appears that we really are sleeping less. In 1960 people in the US slept an average of 8.5 hours per night. A 2002 poll by the National Sleep Foundation suggests that the average has fallen to under 7 hours, and the decline is mirrored by the increase in obesity. 本文来自

There is no denying that ambient temperatures(环境温度) have changed in the past few decades. Between 1970 and 2000, the average British home warmed from a chilly 13C to 18C. In the US, the changes have been at the other end of the thermometer as the proportion of homes with air conditionings rose from 23% to 47% between 1978 and 1997. In the southern states – where obesity rates tend to be highest – the number of houses with air conditioning has shot up to 71% from 37% in 1978. 本文来自

Could air conditioning in summer and heating in winter really make a difference to our weight? 本文来自

Bad news: smokers really do tend to be thinner than the rest of us,and quitting really does pack on the pounds, though no one isn sure why. It probably has something to do with the fact that nicotine is an appetite suppressant and appears to up your metabolic rate.

Katherine Flegal and colleagres at the US National Center for Health Statistics in Hyattsville,Maryland, have calculated that people kicking the habit have been respousible for a small but significant portion of the US epidemic of fatness.From data collected aroud 1991 by the US National Health and Nutrition Examination Survey,they worked out that people who had quit in the previous decade were much more likely to be overweight than smokers and people who had never smoked .Among men, for example, nearly half of quitters were overweight compared with 37% of non-smokers and only 28%of smokers.

4. Genetic effects

Yours chances of becoming fat may be set,at least in part,before you were even born.children of boese mothers are much more likely to become obest themselves later in life.Offspring of mice fed a high-fat diet during pregnancy are much more likely to become fat than the offspring of identical mice fed a normal diet. Intriguingly,the effect persists for two or three generations.Grand-children of mice fed a high-fat diet grow up fat even if their own mother is fed normally-so you fate may have been sealed even before you were conceived.