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 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 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 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 counteract its action.
23. 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
24. The author implies that by 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
25. 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
26. 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. Inventions and innovations almost
always
come out of laborious trial and error. Innovation is like soccer; 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 goal —and so it goes with innovation in any field
of activity. The prime difference between innovation and others is one
of approach. Everybody gets ideas, but innovators work consciously on
theirs and they follow them through until they prove practicable or
otherwise. What ordinary people see as fanciful abstractions, professional innovators see as solid possibilities. Creative thinking may mean simply the realization that there' s no particular virtue in doing things the way they have always been
done, wrote Rudolph Flesch, a language authority. This
accounts for
our reaction to seemingly simple innovations like plastic garbage bags
and suitcases on wheels that make life more convenient: How come nobody
thought of that before?
The creative approach begins with the proposition that nothing is
as it appears. Innovators will not accept that there is only one way
to do anything. Faced with getting from A to B, the average person will
automatically set out on the best-known and apparently simplest route.
The innovator will search for alternate courses, which may prove easier
in the long run and are bound to be more interesting and challenging
even if they lead to dead ends.
Highly creative individuals really do march to a different drummer.
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