"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."
This year, 50 percent of the 910,000 people who suffer from cancer will survive ai least five years. In the year 2000. 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)。
With as many as 120 varieties in existence, discovering how cancer works is not easy. The researchers madegreat progress in the early 1970s. when they discovered that oncogenes. which are cancer-causing genes (基因), are inactive in normal cells. Anything from cosmic rays to radiation to diet may activate a dormant oncogene. but how remains unknown. If several oncogenes are driven into action the cell. unable to turn them off. becomes cancerous.
The exact mechanisms involved are still mysterious, but the likelihood that many cancers are initiated ai the level of genes suggests that we will never prevent all cancers. "Changes are a normal pan 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 cosmic rays. "
The prospects for cure.though still distant, are brighter.
"First we need io 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 al least pan of the trouble. If we can understand how cancer works. we can counteract its action."
1.Robert Weinberg warns that the discovery of the causes or cancer cells won't necessarily lead to_______________________.
2.It is not easy to rind out how cancer works because__________________.
3.Once oncogenes in cells are at work.the cell will become_______________________.
4.By saying "We can't prepare a medicine against cosmic rays", William Hayward implies that it is impossible to avoid che impact of_______________________.
5.Provided that the mechanisms of cancer are found out we are able to_______________________.
答案：
1.[the rapid discovery of its cure]
[定位]根據(jù)題干中的Robert Weinberg和causes查找到第1段第2句。
解析：題干warns對(duì)應(yīng)原文cautions，轉(zhuǎn)折詞But表明Robert Weinberg認(rèn)為，這些人的想法是錯(cuò)的，即他并不認(rèn)為找到了癌癥的成因就能很快的找到該癌癥的治療方法(the rapid discovery of its cure)。
2.[there are 120 varieties of cancer in existence]
[定位]根據(jù)題干中的how cancer works查找到第3段第1句。
解析：原文中的discovering對(duì)應(yīng)題干中的find out，填入的內(nèi)容需在句首with...中找, because后接完整的從句，因此需補(bǔ)上there are。
3.[cancerous]
[定位]根據(jù)題干中的oncogenes查找到第3段最后一句。
解析：題干中的are at work和原文中的are driven into action屬于同義替換，因此照搬原文becomes后的形容詞cancerous即可。
4.[environmental factors]
[定位]根據(jù)題干引號(hào)內(nèi)容查找到第4段最后一句。
解析：原文該句的前一個(gè)分句的內(nèi)容說(shuō)，環(huán)境因素永遠(yuǎn)無(wú)法徹底消除，而接下來(lái)海沃德的話(huà)也說(shuō)明這一點(diǎn)。題干中that從句是對(duì)該段末句的后一個(gè)分句的近義改寫(xiě)。對(duì)比原文與題干，可知environmental factors為本題答案。
5.[counteract its action]
[定位]末段末句。
解析：題干中Provided引導(dǎo)條件句，相當(dāng)于If;被動(dòng)句the mechanisms of cancer are found out和原文understand howcancer works表達(dá)了相同的意思，在這種假設(shè)條件下，原文所說(shuō)的結(jié)果是we can counteract its action，故counteractits action為答案。
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