Why elephants rarely get cancer is a mystery that has confused scientists for decades. A study was led by researchers at Huntsman Cancer Institute (HCI) at the University of Utah and Arizona State University, including researchers from the Ringling Bros. Center for Elephant Conservation may have found the answer. According to the results, elephants have 38 additional modified copies of a gene (基因) that encodes p53, a well-defined tumor (肿瘤) suppressor, as compared to humans, who have only two. Further, elephants may have a more powerful mechanism for killing damaged cells that are at risk for becoming cancerous. In isolated elephant cells, this activity is doubled compared to healthy human cells, and five times that of cells from patients with Li-Fraumeni Syndrome, who have only one working copy of p53 and more than a 90 percent lifetime cancer risk in children and adults. The results suggest extra p53 could explain elephants’ increased resistance to cancer.
“Nature has already figured out how to prevent cancer. It’s up to us to learn how different animals overcome the problem so we can adapt those strategies to prevent cancer in people,” says co-senior author Joshua Schiffman, M.D., pediatric oncologist (肿瘤学家) at Huntsman Cancer Institute, University of Utah School of Medicine, and Primary Children’s Hospital.
According to Schiffman, elephants have long been considered a walking problem. Because they have 100 times as many cells as people, they should be 100 times more likely to have a cell slip into a cancerous state and cause the disease over their long life span of 50 to 70 years. And yet it’s believed that elephants get cancer less often, a theory confirmed in this study. Analysis of a large database of elephant deaths estimates a cancer death rate of less than 5 percent compared to 11 to 25 percent in people.
1.Why do humans often get cancer compared to elephants according to the passage?
A.Elephants are bigger than humans.
B.Elephants have more p53 than humans.
C.Elephants are not as clever as humans.
D.Elephants eat more than humans.
2.Which of the following is right according to the passage?
A.Some damaged cells may be dangerous.
B.Some damaged cells are not dangerous.
C.Some damaged cells can’t be cancerous.
D.Some damaged cells in elephants’ bodies are more dangerous than those in humans’ bodies.
3.What can we know from the last paragraph?
A.Elephants have more cells than people. B.Elephants can get cancer easily.
C.Elephants seldom die from cancer. D.Elephants often die from cancer.
4.Which of the following can be the best title for the passage?
A.Elephants help us B.Learn from Nature
C.How to deal with cancer D.Nature helps us prevent cancer
答案：
1.B
2.A
3.C
4.D
【解析】
这是一篇说明文。文章主要讲述了大象患癌症的几率要远远低于人类，从科学的角度对大象和人类的体内细胞和一些基因进行了对比来说明。
1.细节理解题。根据第一段中According to the results, elephants have 38 additional modified copies of a gene that encodes p53, a well-defined tumor suppressor, as compared to humans, who have only two.（根据研究结果，与只有两个p53基因的人类相比，大象多了38个编码p53基因的修改副本。p53是一种定义明确的肿瘤抑制因子。）可知，大象有38个基因p53，而人类只有两个，所以大象有更强大的机制来杀死受损有癌变危险的细胞。故选B。
2.细节理解题。根据第一段中Further, elephants may have a more powerful mechanism for killing damaged cells that are at risk for becoming cancerous.可知，有些受损细胞会有癌变的危险。故选A。
3.推理判断题。根据最后一段中And yet it’s believed that elephants get cancer less often, a theory confirmed in this study. Analysis of a large database of elephant deaths estimates a cancer death rate of less than 5 percent compared to 11 to 25 percent in people.（然而，据信大象患癌症的几率较低，这一理论在这项研究中得到了证实。对一个大型大象死亡数据库的分析估计，大象的癌症死亡率低于5%，而人类的癌症死亡率为11%至25%。）可知，大象患癌症的几率要远远低于人类。故选C。
4.主旨大意题。根据文章第一段Why elephants rarely get cancer is a mystery that has confused scientists for decades. A study was led by researchers at Huntsman Cancer Institute (HCI) at the University of Utah and Arizona State University, including researchers from the Ringling Bros. Center for Elephant Conservation may have found the answer.（为什么大象很少患癌症是一个困扰了科学家几十年的谜。犹他大学和亚利桑那州立大学亨茨曼癌症研究所(HCI)的研究人员，包括林林兄弟大象保护中心的研究人员，领导了一项研究，可能已经找到了答案。）以及文章主要讲述了大象患癌症的几率要远远低于人类，从科学的角度对大象和人类的体内细胞和一些基因进行了对比来说明。体现了大自然帮助人类预防癌症。分析选项可知A. Elephants help us“大象帮助我们”，文章并未说明大象直接帮助了人类，而是人类通过研究发现大象身上有助于预防癌症的细胞，故A选项不能体现文章主要内容；B. Learn from Nature“向大自然学习”范围太过宽泛，且没有体现文章中提到的大象身上提取的有助于预防癌细胞的事情，故排除B选项；C. How to deal with cancer“如何解决癌症”，文章没有提到直接解决癌症的方法，故不符合文章标题，排除C选项；D. Nature helps us prevent cancer“大自然帮助我们预防癌症”能够体现文章主要内容，故选D。