| Three years ago, researchers announced the discovery
of human genes that were capable of turning ordinary cells into malignant ones.
The news met with some skepticism. Experts asked how a single gene could cause
such a dramatic change. Why does cancer take years or even decades to develop if
it is caused by such a simple and direct process In last week’s issue of the,
three research teams answered those questions by setting forth a new model for
understanding the role of oncogenes in cancer. Each group found that it does in fact take more than a single gene to produce cancer in normal cells. Teams at M. I. T and Cold Spring Harbor Laboratory on Long Island, N. Y. , reported that they could induce cancer in normal rat cells only by inserting at least two types of oncogene into the cells. "A single oncogene produced some changes, A. was caused by normal cells B. sometimes resulted from internal actions of the victim’s own body C. was a hereditary disease D. was a form of malignancy [单项选择]What happened 25 years ago（）
A. Michael’s parents got divorced. B. Karen’s mother died in a car accident. C. A truck driver lost his wife in a collision. D. Karen was adopted by Ray Anderson. [单项选择]Only a few years ago globalization seemed
irrepressible
. We were all advancing on flood tides of international trade and investment.
A. impossible B. possible C. uncontrollable D. improbable [单项选择]What happened to the man four years ago
A. He had a minor operation. B. He had pneumonia. C. He had a car accident. D. He had long aftereffects. [单项选择]An international treaty signed several years ago bans trade in plants and animals of endangered species.
A. forbids B. eliminates C. promotes D. protects [单项选择]
Twelve years ago, oceanographer Captain Charles Moore was skippering his yacht the Alguita in the North Pacific. He sailed into a mass of floating plastic rubbish which took him and his crew a week to cross. This floating rubbish dump is now called the Great Pacific Garbage Patch and doubles the size of the USA. [单项选择]A hundred years ago, chocolate was something
A. that only wealthy people could eat. B. that people all eat like today. C. nobody could afford. 我来回答: 提交
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