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【单选题】
当颁发向河道内排放化学物质的许可证时，它们是以每天可向河道中排放多少磅每种化学物质的形式来颁发的。通过对每种化学物质单独计算来颁发许可证，这些许可证所需的数据是基于对流过河道的水量对排放到河道内的化学物质的稀释效果的估计。因此河道在许可证的保护之下，可以免受排放到它里面的化学物质对它产生不良的影响。以下哪上述论述所基于的假设?( )
A.
相对无害的化学物质在水中不相互反应形成有害的化合物
B.
河道内的水流动得很快，能够保证排放到河道的化学物质被快速地散开
C.
没有完全禁止向河道内排放化学物质
D.
那些持有许可证的人通常不会向河道内排放达到许可证所允许的最大量的化学物质
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D.
No precipitate forms
E.
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A.
acidic
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basic
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装运港    
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A.
NaCN >NaAc>NaF>NaCl>NH 4 Cl
B.
NaF>NaAc>NaCN> NaCl>NH 4 Cl
C.
NaAc>NaCN>NaF>NaCl>NH 4 Cl
D.
NH 4 Cl>NaCl>NaF>NaAc>NaCN
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相关题目：
【单选题】If solutions of calcium iodide and ammonium chloride are mixed together in a metathesis reaction, what is the empirical formula for the precipitate which forms ?
A.
CaCl 2
B.
CaCl
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【简答题】Calculate the approximate pH value of different solutions below ; (1) A 0.10 M HAc K a (HAc)=1.8×10 -5 (2) A 0.10 M NH 4 Cl K b (NH 3 )= 1.8×10 -5 (3) A mixture solution with 0.05 M NaHCO 3 (50 mL...
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【单选题】Which of the following solutions has the highest pH?
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C.
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B.
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C.
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【单选题】按CIF TIANJIN成交的合同，卖方完成交货任务是在(    )。
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装运港    
B.
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【单选题】She has been in Tianjin for ten years. Tianjin has become her second _________.
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B.
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A.
NaCN >NaAc>NaF>NaCl>NH 4 Cl
B.
NaF>NaAc>NaCN> NaCl>NH 4 Cl
C.
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D.
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