Vitamins, like minerals, are chemicals. There is absolutely not difference in the chemical structure 【S1】______ of the natu

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问题     Vitamins, like minerals, are chemicals. There
is absolutely not difference in the chemical structure      【S1】______
of the nature vitamin C and the chemical structure          【S2】______
of the synthetic vitamin C. Also, while most
substances are harmless at very low level of intake         【S3】______
(吸入), all substance—even the elements that are
essential to life—can be dangerous if you overdo
them. Take water for example. Six or eight glasses
a day will keep your body in good fluid balance.
But you can also be drown in it.                            【S4】______
    Some people argue that because individual               【S5】______
vary greatly in their need for nutrients, it can            【S6】______
necessarily be stated that any given amount is too
much; that is all relative. But since there is little
solid information on what is the optimum intake
of any essential nutrient in healthy individuals, it
would be impossible to give guidelines that take
these proportional needs into count.                        【S7】______
    Just as with other drags, the relation to different     【S8】______
vitamin dosages varies, with some people better able
than others to tolerate large amounts. While we do
know that very specifically what the toxic level is         【S9】______
for vitamins A and D, we are far less sure about
vitamin E, even though it, too, is fat-soluble, and
we still don’t understand the water-soluble vitamins,
the C or the B groups, which the body can’t store.          【S10】______
【S3】

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答案∧ very→a

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