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【简答题】
某分析人员取 10.00 mL 工业废水样,在 50 mL 容量瓶中稀释至标线,摇匀。取稀释后水样 20.00 mL 加入 10.00 mL0.0250mol/L 重铬酸钾溶液,按操作步骤测定,回流后用蒸馏水稀释至 140mL ,以 0.1033mol/L 硫酸亚铁铵标准溶液滴定,消耗 23.15 mL ,全程序空白测定消耗该标准液 24.92 mL 。求该种工业废水的 COD Cr 值为多少?
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【简答题】People living on parts of the south coast of England face a serious problem. In 1993, the owners of a large hotel and of several houses discovered, to their horror, that their gardens had disappeared ...
【简答题】People living on parts of the south coast of England face a serious problem. In 1993, the owners of a large hotel and of several houses discovered, to their horror, that their gardens had disappeared ...
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A.
均衡价格下降，均衡数量减少
B.
均衡价格上升，均衡数量减少
C.
均衡价格下降，均衡数量增加
D.
均衡价格上升，均衡数量增加
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A.
While
B.
skilled talents
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overriding
D.
at heavy demand
【单选题】若图中闭合等高线的高度同为 a 或同为 b ,则 M 、 N 处的地形可能( ) 1 同为洼地 2 同为小丘 3 同为缓坡 4 一处为小丘,一处为洼地
A.
①②
B.
①③
C.
①④
D.
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