B．锌是负极，碳棒是正极
C．废旧锌锰干电池没有回收价值
答案：C
曲线y2=2z，x=0绕z轴旋转一周，所得到的曲面方程为（）。
A.x2-y2=2z
B.x2+z2=2y
C.x2+y2=2z
D.z2+y2=2x
By 16:30, ______ was almost closing time, nearly all the paintings had been sold.[ ]
A. which
B. when
C. what
D. that
锌锰干电池没有回收价值