easy. The researchers made great progress in the early 1970s, when they disoovered that oncogenes, which are cancer-causing genes (基因) , are inactive in normal cells. Anything from cosmic rays to radi-
ation 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 at the level of genes suggests that we will never prevent all cancers. "Changes are a nor- mal part of the evoLutionary process , " says oncologist William Haywar. 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 to understand how the normal cell controls itself. Second, we have to deter- mine whether there are a limited number of genes in cells which are always responsible for at leasl part of the trouble. If we can understand how cancer works, we can counteract its action. "
63. The example of Pasteur in the passage is used to__.
A. predict that the secret of cancer will be disclosed in a decade
B. indicate that the prospects for curing cancer are bright
C. prove that cancer will be cured in fifty to sixty years
D. warn that there is still a long way to go before cancer can be conquered
64. The author implies that bv the year 2000 ,__.
A. there will be a drastic rise in the five-year survival rate of skin-cancer patients
B. 90 percent of the skin-cancer patients today will still be living
C. the survival statistics will be fairly even among patients with various cancers
D. there won' t be a drastic increase of survival rate of all cancer patients
65 . Oncogenes are cancer-causing genes__.
A. that are always in operation in a healthy person
B. which remain unharmful so long as they are not activated
C. that can be driven out of normal cells
D. which normal cells can' t turn off
66 . The word "dormant" in the third paragraph most probably means__.
A. dead B. ever-present C. inactive D. potential
Passage 5
Discoveries in science and technology are thought by "untaught minds" to come in blinding flashes or as the result of dramatic accidents. Sir Alexander Fleming did not, as legend would have it, look at the mold (霉) on a piece of cheese and get the idea for penicillin there and then.
He experimented with antibacterial substances for nine years before he made his discovery. Inven- tions and innovations almost always come out of laborious trial and enor. Innovation is like soc- cer; even the best players miss the goal and have their shots blocked much more frequently than
they score.
The point is that the players who score most are the ones who take most shots at the and so it goes with innovation in any field of activity. The prime difference between innovation a
[责任编辑:bulesky]
- 更多相关此主题的新闻
-
·2008年职称英语考题预测及复习重点 2008-02-21 ·2008年MBA联考英语真题及答案 2008-01-20 ·英语写作综合精练：说写听读都重要 2008-01-05 ·徐绽：08考研英语写作核心精析 2007-12-27 ·考研英语冲刺阶段 词汇复习最重要 2007-12-18 ·2007年全国硕士研究生入学考试英语试题及参 2007-12-13
| 资源站推荐资料 | |||||||||
| |||||||||
一周热点
考研
英语
| ·2008硕士研究生入学统一考试政治模拟试题(三 |
| ·2008年考研政治试题预测之哲学23题 |
| ·2008年考研政治试题预测之邓论24题 |
| ·考研英语作文预测 |
| ·考研政治哲学与十七大报告重点理论热点 |
| ·2008年考研政治试题预测之政经21题 |
| ·海文王海军：08考研时事政治国内时事预测题 |
| ·2008年考研政治试题预测之毛概16题 |
| ·2007年12月英语六级考试真题（B卷） |
| ·2007年12月大学英语六级B卷试题答案 |
| ·2007年12月大学英语六级A卷权威答案 |
| ·英语四级考试写作必背十大范文 |
| ·2005年1月六级真题解析[图] |
| ·2005年12月英语六级考试试题含答案[图] |
| ·英语四六级考前短期迅速突破法 |
| ·大学英语四级短期冲刺高分的绝招！ |
推荐新闻
- 论坛看点
