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问题 选择题

下列各溶液中跟300ml0.8mol/L的NaCl溶液中Cl-的物质的量浓度相同的是（　　）

A．100mL1.2mol/L的MgCl2溶液

B．600mL0.4mol/L的NaCl溶液

C．0.4L0.3mol/L的BaCl2溶液

D．1L0.8mol/L的HCl溶液

答案

A、100mL1.2mol/L的MgCl2溶液中氯离子浓度=1.2mol/L×2=2.4mol/L；

B、600mL0.4mol/L的NaCl溶液中氯离子浓度=0.4mol/L；

C、0.0.4L0.3mol/的BaCl2溶液中氯离子浓度=0.3mol/L×2=0.6mol/L；

D、1L0.8mol/L的HCl溶液中氯离子浓度=0.8mol/L；

综上所述可知D选项中氯离子的浓度与之相同；

故选D．

问答题

　In the coming decades, Europe’s influence on affairs beyond its borders will be sharply limited, and it is in other regions, not Europe, that the 21st century will be most clearly forged and defined. Certainly, one reason for NATO’s increasing marginalization stems from the behavior of its European members. With NATO, critical decisions are still made nationally; much of the talk about a common defense policy remains just that — talk. There is little specialization or coordination. Missing as well are many of the logistical and intelligence assets needed to project military force on distant battlefields. With the Cold War and the Soviet threat a distant memory, there is little political willingness, on a country-by-country basis, to provide adequate public funds to the military.

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单项选择题

混凝土外加剂性能检验，凝结时间差测定，凝结时间取三个试样的平均值。若三批试验的最大值或最小值之中有一个与中间值之差超过（），把最大值与最小值一并舍去，取中间值作为该组试验的凝结时间。

A.15min

B.30min

C.45min

D.60min
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