.
All the tickets have been sold out. ______ is left.
A.No one
B.Nothing
C.None
D.Not anyone
C
如果关于x的方程4mx2-mx+1=0有两个相等实数根,那么它的根是 ______.
钢材中残余元素铬、镍、铜的含量不应大于( )。
A.0.10%
B.0.20%
C.0.30%
D.0.40%