"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 made great 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."

　　測試題

　　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_______________________.

　　答案詳解

　　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對應(yīng)原文cautions，轉(zhuǎn)折詞But表明Robert Weinberg認為，這些人的想法是錯的，即他并不認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)題干引號內(nèi)容查找到第4段最后一句。

　　解析：原文該句的前一個分句的內(nèi)容說，環(huán)境因素永遠無法徹底消除，而接下來海沃德的話也說明這一點。題干中that從句是對該段末句的后一個分句的近義改寫。對比原文與題干，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;被動句the mechanisms of cancer are found out和原文understand how cancer works表達了相同的意思，在這種假設(shè)條件下，原文所說的結(jié)果是we can counteract its action，故counteract its action為答案。

　　參考譯文

　　“我很有把握，到本年代末，我們會非常詳細地了解到癌細胞是如何產(chǎn)生的，”癌癥專家、微生物學(xué)家羅伯特·溫伯格說。[1]“但是，”他警告說，“有些人認為，一旦有人找到了病因，治療方法馬上就隨之而來了。想想巴斯德吧!他發(fā)現(xiàn)了許多種感染的原因，但是五六十年后才找到治療方法。”

　　今年，患癌癥的91萬人中，有50%至少可以活5年。國家癌癥研究所估計，到2000年，這個比例將上升到75%。在患某些皮膚癌的人中，5年存活率高達90%。但是其他癌癥患者中能活5年的人所占比例仍令人沮喪——肺癌為13%，胰腺癌為2%。

　　[2]因為已發(fā)現(xiàn)的癌癥種類多達l20種，要找出癌癥是如何發(fā)生的并不容易。20世紀70年代初，研究人員取得了重大進展。他們發(fā)現(xiàn)，致癌基因——誘發(fā)癌癥的基因——在正常細胞中不活躍。任何因素，包括宇宙射線、輻射、飲食，都可能激活不活躍的致癌基因。但激活的機制尚無人知曉。[3]如果幾個致癌基因被激活，細胞無法將其阻斷，就發(fā)生癌變。

　　其中確切的機制仍是一個謎，但一種可能性是，許多種癌癥是從基因?qū)哟伍_始的，這說明，我們將永遠無法防止所有的癌癥發(fā)生。“進化過程中發(fā)生變化是很正常的事，”腫瘤學(xué)家威廉·海沃德說。[4]環(huán)境因素永遠也無法徹底消除;正如海沃德指出的，“我們無法制出藥物來防止宇宙射線。”

　　治療方法前景雖然還很渺茫，但畢竟樂觀一些了。

　　“首先，我們必須弄清楚，正常細胞如何自我控制。其次，我們得確定，是不是至少有部分麻煩總是由細胞中數(shù)量不多的一些基因所致。[5]如果我們能弄清楚癌癥是如何起作用的，我們就可以抑制其活動。”