题目

等物质的量的主族金属A、B、C分别与足量的稀盐酸反应，所得氢气的体积依次为VA、VB、VC，已知VB=2VC，VA=VB+VC，则金属C元素所在的主族是A．ⅠA         B．ⅡA           C．ⅢA         D．无法确定   答案：A解析: —I missed the first part of the film .It was really a pity.—You ________home half an hour earlier.A．should have left B．must have leftC．should leave D．must leave