This passage is probably taken from ______.
A. a text book
B. an introduction to a book
C. a scientific report
D. an interview with two leading scientists in medicine
After the improvement of the hospital environment, patients ______.
A. no longer need drugs in their recovery
B. are not wholly dependent on expensive drugs
C. need good-quality drugs in their recovery
D. do not use pain killers in their recovery
"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 at 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 statistic(统计)rate 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 ceils. 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 suggest that we will never prevent all cancers. "Changes are a normal part of the evolutionary process," says oneologist 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 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."
According to Robert Weinberg, which of the following is true?
A. Cures for cancer will soon be found if we know how cancer cells arise.
B. We' 11 have to wait fifty or sixty years before we understand the Causes of cancer.
C. Even when we understand the causes of cancer, that doesn't mean we will soon find a cure for cancer.
D. We won't understand the causes of cancer before the end of the decade.