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单选题

A．The impact of smoking lasts less than 30 years.
B．Smoking has a long-term impact on Our molecular machinery.
C．Damages caused by smoking can never be cured.
D．Ailments are mainly caused by damage to the DNA.

参考答案B

解析:Researchers at Harvard Medical School’s affiliated Hebrew SeniorLife Institute for Aging Research say smoking leaves a long—term signature on DNA．
(23)"Our study has found compelling evidence that smoking has a long-lasting impact on our molecular machinery，an impact that can last more than 30 years，”said Roby Joehanes，first author on the study．“The encouraging news is that once you stop smoking．the majority of DNA methylation signals return to never smoker levels after five years，which means your body is trying to heal itself of the harmful impacts of tobacco smoking．"
Ajlments,including heart disease and cancer．are believed to be at least partially caused by damage to the DNA．
(24)For the study．the researchers looked at blood samples from 16,000 people．They found that for most.the DNA damage caused by smoking faded for people who had kicked the habit for five years．Some of the damage appeared to be permanent．
The damage to DNA is a result of a process called methylation,which changes how DNA functions．
possibly leading to cancer and other illnesses．The researchers say that smokers，among those studied,saw changes to more than 7,000 genes or about one．third of known human genes．
“These results are important because methylation,as one of the mechanisms of the regulation of gene expression，affects what genes are turned on，which has implications for the development of smoking，related diseases，”(25)said Dr．Stephanie J．London,last author and deputy chief of the epidemiology branch at the National Institute of Environmental Health Sciences，National Institutes of Health．“Equally important is our finding that even after someone stops smoking．we still see the effects of smoking on their DNA．”
Smoking is the leading cause of preventable illness and kills an estimated 480,000 Americans annually．The Centres for Disease Control and Prevention said．Smoking is believed to take the lives of more than 6 million people every year across the globe，mostly through cancer，heart disease and lung disease．
In the United States，smoking levels have dropped considerably，with only all estimated 15 percent of the adult population engaging in the habit．
According to Roby Joehanes，what has the study found? B。

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单选题

A．They checked the lungs of 16,000 people.
B．They examined the heartbeats of 16,000 smokers.
C．They measured the blood pressure of 16,000 smokers.
D．They looked at blood samples from 16,000 people.

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单选题

A．The effects of smoking on their DNA still exists.
B．The damage to their DNA will be cured one year later.
C．The function of their DNA has been changed.
D．The chance of having cancer is still high.

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单选题Questions are based on the following passage.
There is much discussion today about whether economic growth is desirable. At an earlier period, our desire for material wealth may have been（26）. Now, however, this desire for more than we need is causing serious problems（27）Even though we have good（28）, we may be producing too much, too fast. Those who criticize economic growth argue that we must slow down. They believe that society is（29）certain limits on growth. These include the fixed supply of natural resources, the possible（30） effects of industry on the natural environment, and the continuing increase in the world's population. As society reaches these limits, economic growth can no longer continue, and the quality of life will（31）.
People who want more economic growth, on the other hand, argue that even at the present growth rate there are still many poor people in the world. These（32） of economic growth believe that only more growth can create the capital needed to improve the quality of life in the world. Furthermore, they argue that only continued growth can provide the（33） resources required to protect our natural surroundings from industrialization.
This debate over the desirability of continued economic growth is of（34）importance to business and industry. If those who argue against economic growth are Correct, the problems they mention cannot be（35）.
To find a solution, economists and the business community must pay attention to these problems and continue discussing them with one another.
A. approaching
B. constantly
C. decrease
D. enlarge
E. financial
F. fundamental
G. ignorant
H. ignored
I. intention
J. justified
K. negative
L. positive
M. proponents
N. rigidly
O. Specification
第（26）题选

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