| 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]Ten days ago the young man informed his boss of his intention to （）
A. resign B. reject C. retreat D. replace [单项选择]When did the woman give up smoking
[A] Ten days ago. [B] Just this morning. [C] A week ago. [D] Just yesterday. [单项选择]
[单项选择]
A. (A) A kiss. B. (B) Her keys. C. (C) A briefcase. D. (D) A locket. [单项选择]Who are the woman and the man
A. Husband and wife. B. Mother and ion. C. Friends. [单项选择]
A. Her new address. B. Her company’ s name. C. Her email. D. Her phone number. [单项选择]Why does the woman thank the man
A. He lent her some money. B. He gave her a five-pound bill. C. He returned her money found. [单项选择]What does the woman tell the man
A. He has to do what is necessary in order to learn. B. He doesn’t have to memorize all the vocabulary. C. There is not much he can learn by memorizing. D. He knows the whole vocabulary list already. [单项选择]Will the woman help the man now
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