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【简答题】
用酸处理 l.00 g 谷物制品试样,加入少量 KMnO 4 ,将核黄素氧化,过量的 KMnO 4 用 H 2 O 2 除去 将此溶液移入 50 ml 容量瓶中。吸取 25 ml 放入样品测定荧光强度。事先将荧光计用硫酸奎宁调至刻度 100 。测得氧化液的读数为 5.0 。加入少量连二亚硫酸钠( Na 2 S 2 O 4 ),这时荧光计读数为 57 。在另一样品重新加入 24 ml 被氧化的核黄素溶液,以及 1 ml 核黄素标准溶液( 0.5μg/ml ),这一溶液的读数为 90 试计算试样中核黄素的质量分数( μg/g) 。
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【单选题】Students buying a car should take into account ______.
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the interest of the loan
B.
insurance costs
C.
the age of the car
D.
the family objections
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A.
how to determine the amount of additional insurance you would need
B.
life insurance is the result of the amount of additional insurance you'll need to buy
C.
life insurance is most important in maintaining your family's current life-style
D.
life insurance isn't fun to buy
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【单选题】The following statements can be inferred from the passage EXCEPT that______
A.
some insurance and security companies make a big profit in kidnapping insurance
B.
the insurance policies have created a way for the kidnappers to make more money
C.
kidnappers are oblivious of the insurance policies
D.
an employee often buys insurance for all his or her family members
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