题目

下列各组离子中，能在同一溶液中大量共存，加入一小块钠后仍能大量共存的是（    ） A . Na+、K+、Cl﹣、CO32﹣ B . Cu2+、Na+、SO42﹣、CO32﹣ C . Ba2+、K+、Cl﹣、SO42﹣ D . K+、Na+、HCO3﹣、NO3﹣ 答案：AWhen the police arrived on the scene, there was quite a crowd of ________．A.looker - onsB.looker - onC.lookers - onD.the looker - on