正确答案: B

增殖并分化成多种细胞

题目：骨髓移植是治疗白血病常用的有效方法之一，最主要的原因是移植骨髓中的造血干细胞可在患者体内

解析：B

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学习资料的答案和解析：

[单选题]我国的全国人大代表，来自各地区、各民族、各方面，工人、农民、知识分子、解放军和妇女、归国华侨等都有适当的比例，人口再少的民族也至少有一名代表。这表明我国民主具有

广泛性

[单选题]下列各句中，加点的成语使用不恰当的一项是

身处春秋鼎盛的时代，我们这些身强力壮的青年应该奋发有为，积极向上，刻苦学习，为国家和社会多作贡献。

[单选题]西方历史哲学家柯林伍德指出：“一切历史都是思想史。”在这里，柯林伍德强调的是

历史学离不开人的主观判断

[单选题]D On May 23,1989, Stefania Follini came out from a cave at Carlsbad , New Mexico. She hadn’t seen the sun for eighteen and a half weeks . Stefania was in a research program, and the scientists in the program were studying body rhythms (节奏)。In this experiment Stefania had spent 130 days in a cave ,30 feet in depth.During her time in the cave, Stefania had been completely alone except for two white mice. Her living place had been very comfortable ,but there had been nothing to fell her the time .she’d had no clock or watches , no television or tadio. There had been NO natural light and the temperature had always been kept at 21℃

she was the subject of astudy

[单选题]根和茎在形成次生结构后，未被破坏的初生结构是( )。

初生木质部