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【单选题】
Which sentence below best expresses the essential information in the highlighted sentence in paragraph 4? Incorrect choices change the meaning in important ways or leave out essential informationA.
The wetlands completely cover the landscape, making it difficult to grow crops and grass for grazing
B.
The native grasses that grew in the potholes have been replaced with crops that are more beneficial
C.
Except for the potholes region, the entire prairie has been converted to cropland and grazing land
D.
Even though a large portion of the prairies is used for crops and grazing, the small ponds remain
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【单选题】维生素B12注射液规格为1ml:0.1mg,含量测定方法如下:精密量取本品7.5ml,置25ml量瓶中,加蒸馏水稀释至刻度,混匀,置1cm石英池中,以蒸馏水为空白,在(361±1)nm波长处测得吸收度为0.593,以 为207,计算得维生素B12相当于标示量的百分含量为
A.
90%
B.
92.5%
C.
95.5%
D.
97.5%
E.
99.5%