题目

People are decorating the front doors with Spring Festival couplets. （Rewrite the following sentences in the passive voice.） 答案：The front doors are being decorated with Spring Festival couplets.已知某强酸性溶液中存在较多的Ba2+、NO3－，则溶液中还可能大量存在的离子组是A．K+、NH4+、HCO3－ B．Na+、Cu2+、Cl－C．Cu2+、Mg2+、SO42－ D．Fe2+、Ca2+、Cl－