能正确表示下列反应的离子方程式的是（ ）
A．硫酸铜与氢氧化钠溶液反应：CuSO4+2OH-═Cu（OH）2↓+SO42-
B．碳酸钡与过量硫酸溶液反应：Ba2++SO42-═BaSO4↓
C．二氧化硅与氢氧化钠溶液反应：SiO2+2OH-=SiO32-+H2O
D．单质铁与硫酸铜溶液反应：2Fe+3Cu2+=2Fe3++3Cu
A、硫酸铜与氢氧化钠溶液反应，硫酸铜为可溶物，反应的离子方程式为：Cu2++2OH-=Cu（OH）2↓，故A错误；
B、碳酸钡与过量硫酸溶液反应，碳酸钡应该保留化学式，正确的离子方程式为：2H++BaCO3+SO42-═BaSO4↓+H2O+CO2↑，故B错误；
C、二氧化硅与氢氧化钠溶液反应生成硅酸钠，反应的离子方程式为：SiO2+2OH-=SiO32-+H2O，故C正确；
D、单质铁与硫酸铜溶液反应生成亚铁离子，反应的离子方程式为：Fe+Cu2+=Fe2++Cu，故D错误；
故选C．
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| The birthrate in Europe has been in a steady decrease since the 1960s. European countries, realizing crisis is at hand, are providing great encouragement for parents to create more babies in the 21st century. Affairs Ministry concluded last year that, 1 cash encouragement, some women just don't want to be 2 holding the baby. "What we know is that it's good for the 3 if men and women share the burden of having children," says Soren Kindlund, family policy adviser at the Swedish ministry. 4 Swedish parents can take their paid leave as they wish, men use a mere 12% of it; 60% of fathers do not take even a(n) 5 day off work. Experts fear that the tendency for women to use most of the parental leave could make employers 6 go give young women the permanent jobs they need to qualify for paid maternity leave (产假). In January. Sweden decided to allow new fathers two months' paid leave, with a warning: use it or 7 it. Kindlund admits that men are under 8 to stay at work, even though parental pay comes out of the public purse. "It's not popular among bosses and perhaps with other men in the workplace," he says. "But it's good for the father and for the child if they can 9 a relationship." In Norway, a(n) 10 policy has worked wonders. 70% of dads in Norway now take parental leave, and the birthrate of 1.85 children per woman is one of the highest in Europe. | ||||
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4NO(g)＋6H2O(g)； △H＝－905 kJ/mol……①