【单选题】
在职业性放射疾病中，发展为白血病的情况最有可能是因为（ ）。
①
一次接受少量的电离辐射
②
一次接受超量的电离辐射
③
长期接受总量少量的电离辐射
④
长期接受总量超量的电离辐射
【单选题】
佝偻病的发生是由于缺乏（ ）．
①
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②
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③
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④
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