题目

 --Why are you taking a basket with you for shopping?      --The stores doesn't_______ plastic bags for shoppers to protect the environment.   A. sell                B. support                    C. provide                        D. collect 答案：C向pH为4的盐酸中加入下列物质，混合后溶液的pH可能会减小的是 [     ]A．纯水B．氢氧化钠溶液 C．pH为4的盐酸 D．硫酸溶液