Who are usually considered the best donors for bone marrow transplant?

A．Parents．

B．Brothers and sisters．

C．Registered donors．

D．Healthy donors．

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参考答案

B。本题的出题点在因果关系处(because…）。根据题干信息词the best donors将答案锁定在文章第三段首句，该句的意思是：为防止出现移植后的排异现象，家庭成员，特别是兄弟姐妹，是骨髓移植的首选捐赠者，因为他们细胞中的遗传标记相同的概率较高。siblin9指“兄弟姐妹”，故B正确。

1 What should be done immediately after the matched donor has been found?

A．Unhealthy cells of the patient are killed through radiation or chemotherapy．

B．Healthy cells are extracted from the donor．

C．Extracted cells are prepared in the laboratory．

D．The donor's cells are transplanted to the patient．

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2 The healthy cells of donors will be transplanted to the patient through __

A．pelvic bones

B．arms

C．vein

D．artery

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3 The author cited the example of 4．8 million volunteer donors in America to justify __．

A．all the patients will be able to get transplant treatment

B．there are more patients who need transplant

C．it becomes much easier to find suitable donors for the patients

D．it is hard to find suitable match even with the large pool of donors

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