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A. Attention must be paid to environmental factors.

B. Principles of curing cancers.

C. It will take long to find perfect cures.

D. An important discovery in the research.

E. The causative factor of cancer is very clear.

F. The survival rate differs among patients with various cancers.

小题1:___________

“I have great confidence that by the end of the decade we’ll know in vast detail how cancer cells arise,” says microbiologist Robert Weinberg, an expert on cancer. “But,” he cautions, “some people have the idea that once one understands the causes, the cure will rapidly follow. Consider Pasteur. He discovered the causes of many kinds of infections, but it was fifty or sixty years before cures were available. ”

小题2:____________

This year, 50 percent of the 910,000 people who suffer from cancer will survive at least five years. In the year 2020, the National Cancer Institute estimates, that figure will be 75 percent. For some skin cancers, the five-year survival rate is as high as 90 percent. But other survival statistics are still discouraging—13 percent for lung cancer, and 2 percent for cancer of the pancreas (胰腺) .

小题3:___________

With as many as 120 varieties in existence, discovering how cancer works is not easy. The researchers made great progress in the early 1970s, when they discovered that oncogenes, which are cancer-causing genes, are inactive in normal cells. Anything from universe rays to radiation to diet may activate an inactive gene, but how remains unknown. If several oncogenes are driven into action, the cell, unable to turn them off, becomes cancerous.

小题4:____________

The exact process involved is still mysterious, but the likelihood that many cancers are initiated at the level of genes suggests that we will never prevent all cancers. “Changes are a normal part of the evolutionary process,” says oncologist William Hayward. Environmental factors can never be totally eliminated; as Hayward points out, “We can’t prepare a medicine against universe rays.”

小题5:____________

The prospects for cure, though still distant, are brighter. “First, we need to understand how the normal cell controls itself. Second, we have to determine whether there are a limited number of genes in cells, which are always responsible for at least part of the trouble. If we can understand how cancer works, we can reduce its action. ”

自由下落的物体，在落地前的最后一秒内下落了 ，不计空气阻力，问此物体是从离地多高的地方开始下落的？（）

某型号的泡壶正常工作时的额定电流      A；泡茶壶有80%的电能被水吸收，壶中装满温度为20℃的水，在标准大气压下将水烧开需要电能      J，共需要      s。（计算结果保留一位小数）

敏感性分析与风险分析的主要区别在于( )。

A．两者的分析结果、方法和作用不同

B．两者的分析内容、方法和作用不同

C．两者的分析内容及分析结果不同

D．两者的分析方法和作用不同

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