题目

       My husband hasn’t stopped laughing about the thing that happened to me. It’s  16   now but it wasn’t that time. Last Friday, after doing all the family shopping in town, I  17  a rest before catching the train, so I bought a   18  and some chocolate and went to the station coffee shop that was a cheap, self-service place with long   19  to sit at. I put my heavy bag down on the floor, put the newspaper and chocolate on the table to   20  a place and went to get a cup of coffee. When I came back with the coffee, there was someone in the   21   seat下列离子方程式书写正确的是 （　 ）A．向Ba(OH)2溶液中逐滴加入NH4HSO4溶液至刚好沉淀完全：Ba2+ + OH- + H+ + SO42- = BaSO4↓+ H2OB．将过量的NaOH溶液滴入同浓度的少量Ca(HCO3)2溶液Ca2＋ + 2HCO3―+2OH―=CaCO3↓+ 2H2O + CO32―C．醋酸钡溶液和硫酸反应：Ba2＋＋SO42-= BaSO4↓D．向酸性FeSO4溶液中加H2O2溶液: 2Fe2+ + 2H2O2 + 4H+ =2Fe3+ + 4H2O