题目

下列实验能达到预期目的的是(    ) ①用乙醇和浓硫酸除去乙酸乙酯中的少量乙酸  ②将Cl2的制备和性质实验联合进行以减少实验中的空气污染  ③用食醋和澄清石灰水验证蛋壳中含有碳酸盐  ④用硝酸钡溶液鉴别硫酸根离子与亚硫酸根离子  ⑤用溴水检验汽油中是否含有不饱和脂肪烃A.①②③                  B.①③④                  C.②③⑤                D.②④⑤.The teacher demanded that our examination paper _____handed in at once . A be  B must be   C would be   D had to be