2. 外语
  3. In recent years, researches have suggested more health value from vitamin D than had once been thought. Vitamin D is【C1】____

In recent years, researches have suggested more health value from vitamin D than had once been thought. Vitamin D is【C1】____

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问题     In recent years, researches have suggested more health value from vitamin D than had once been thought.
    Vitamin D is【C1】______naturally in the blood. Sunlight is a【C2】______source. It is also found in some foods. Vitamin D helps to increase levels of calcium in the blood. It helps build strong bones and teeth.
    It also【C3】______to do more than just protect against rickets(软骨病). That serious bone disease was the reason why vitamin D was added to milk. Rickets is now【C4】______in the western world. But it is still a common childhood disease in developing countries. Rickets can and is also【C5】______to cause bone pain and weakness, teeth problems and muscle【C6】______.
    According to the study by the Harvard School of Public Health, Vitamin D might protect against multiple sclerosis(多发性硬化症). also called MS.
    MS is a【C7】______disease of the central nervous system that【C8】______about two million people around the world. There is no【C9】______. The level of severity can differ from person to person. But is usually seriously disabling.
    The study in Boston found that people with higher levels of vitamin D had lower【C10】______of MS. It found that the chance of developing MS was sixty-two percent lower among those with the highest level of vitamin D【C11】______those with the lowest level.
    Vitamin D may become a future【C12】______for MS. But, he says first scientists must carry【C13】______a large, controlled study in which some people get vitamin D and others【C14】______not.
    This is not the first study to show a possible【C15】______between vitamin D and multiple sclerosis. But it has【C16】______the clearest evidence of a direct【C17】______. The National Institutes of Health says some studies also suggest vitamin D【C18】______protect against some kinds of【C19】______. But it says more human studies are needed to learn if a lack of vitamin D【C20】______the risk of cancer.
【C18】
选项 A、may
B、should
C、can
D、must
答案A
解析
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