問題詳情

B.At three laboratories in Boston, the world of stem cell research can be captured in all its complexity, promise anddiversity. One of the labs focuses on cells taken from human embryos, another on cells from mice and fish, and a thirdfrom stem cells that have mysteriously survived in the adult body long after their original mission is over. One idea, the focus of about half the stem cell research in the United States, involves studying stem cells that arenaturally present in adults. Researchers have found such cells in a variety of tissues and organs and say they seem to be apart of the body’s normal repair mechanism. The other line of research, with stem cells from embryos, has a differentobstacle. Although, in theory, the cells could be 16 into developing into any of the body’ s specialized cells, so farscientists are still working on ways to direct their growth in the laboratory and they have not yet effectively cure diseases,even in animals. The most progress with embryonic stem cells is in mice, 17 one group of researchers directed thecells to grow into a variety of blood cells, but not yet the ones they want. Another group directed mouse stem cells to growinto nerve cells and tried to use them to treat Parkinson’s disease in mice. The nerve cells produced the missing chemical,dopamine, but not enough to cure the disease. Dr. Bianchi knew that a few fetal cells enter a woman’s blood during pregnancy and discovered that the fetal cells donot disappear when a pregnancy ends. Instead, they remain in a woman’s body for decades, perhaps 18 . If a woman’stissue or organs are injured, fetal cells from her baby migrate there, divide and turn into the needed cell type. In theory,fetal cells lurking in a woman’s body are the 19 of a new source of stem cells and could be stimulated to treatdiseases. But, Dr. Bianchi says, she does not yet know for sure that the cells are stem cells.  In the basement of a biology building on Harvard’s campus, a small group of scientists is creating human embryos bycloning and obtaining stem cells from those embryos. While many Americans say in polls that they favor using these cells,many others have strong moral objections. Creating and destroying a human embryo to obtain stem cells, they say, isethically unacceptable, and doing research on human embryonic stem cell lines does not 20 the wrong.The challenge for scientists, in the midst of fierce political debate, many say, is to be realistic about how hard it is todevelop treatments.
16.
(A) coaxed
(B) delved
(C) pummeled
(D) cogitated

參考答案

答案：A
難度：困難0.363636
統計：A(4),B(3),C(1),D(1),E(0)

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