D
Since the gene, called DAF-16 in worms, was found in many animals and in humans, the finding could open up new ways to affect aging, immunity(免疫)and resistance in humans, the scientists said.
“We wanted to find out how normal aging is being governed by genes and what effect these genes have on other traits, such as immunity,” said Robin May of the University of Birmingham, who led the study.
Populations across the world are aging at a surprising pace, bringing potentially big challenges for health and social care systems. A study by Danish scientists last year found that half of babies born in the rich world today will live to celebrate their 100th birthdays. Scientists are eager to find out how people age to try to develop drugs to help them stay healthier as their lives extend.
“What we have found is that things like resistance and aging tend to go hand in hand,” May said in an interview.
May’s team compared longevity, stress resistance and immunity in four related species of worm. They also looked for differences in the activity of DAF-16 in each of the four species, and found that they were all quite distinct.
May said DAF-16 was active in most cells in the body and was very similar to a group of human genes called FOXO genes, which scientists believe play a role in the aging process.
“The fact that subtle（微妙的）differences in DAF-16 between species seem to have such an impact on aging and health is very interesting and may explain how differences in lifespan and related traits have arisen during evolution,” May said.
71. In which section may the text appear in a newspaper? 
A. Education.              B. Science.          C. Entertainment.         D. Culture.
72. According to May_________,.
A. resistance has a lot to do with aging         
B. FOXO genes can be found in worms
C. genes play the same role in different species
D. new drugs will change the genes in older people
73. What can we know from the third paragraph?
A. New ways have been found to affect aging. 
B. Babies in the rich world will all live longer. 
C. Present social care systems are poorly managed.
D. Aging populations are causing more challenges.
74. From the text we know that DAF-16.
A. is a gene that is only found in worms     B. can make people live longer
C. has an effect on aging and immunity     D. has been quite familiar to scientists
75. What can be the best title of the passage?
A. Scientists Find Gene Linked to Aging          B. Population Aging Faster than Expected
C. How to Make People Live Longer             D. Gene Determines How Long We Live