| 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]
In just three years, the Net has gone from a playground for the local people to a vast communications and trading center where millions swap information or do deals around the world.（） A. business B. shopping C. chatting D. meeting [单项选择]He went（）to study（）after he graduated from the university.
A. abroad...further B. abroadly...furtherly C. abroad... furtherly D. abroadly...further [单项选择]He has been away from home ______ three months ago.
A. since B. for C. during D. before [单项选择]His mother（）for three years.
A. died B. was dead C. has been dead [单项选择]"He graduated from English Department, Beijing University. " illustrates the fact that English differs from Chinese in （ ）.
A. branching sentence patterns B. paratactic relations C. word order D. number and case [填空题]Henry had to walk home from work because he missed the bus．
Henry didn’t______the bus SO he had to walk home from work． [单项选择]Divorced from his wife just three months ago, he has made quite a （ ） of himself by gallivanting about with his new girlfriend, a former supermodel.
A. improvidence B. revelation C. extravagance D. spectacle [单项选择]Many years had ______ before they returned to their original urban areas.
A. floated B. elapsed C. skipped D. proceeded 我来回答: 提交
|
