题目

Patrick waited all the luggage was cleared, but his never appeared. A . until B . before C . when D . while 答案：A不定项有10g不纯CaCO3样品与足量盐酸作用后生成4.44gCO2，且溶液中残留难溶物质。则对于此样品中是否存在①MgCO3 ②K2CO3 ③SiO2杂质的判断正确的是A．肯定含①③，不含②B．肯定含①③，可能含②C．肯定含②③，不含①D．肯定含②③，可能含①