根据规定,饰面砖样板件,每组试样平均黏结强度不应小于( )。
A.0.1MPa
B.0.2MPa
C.0.3MPa
D.0.4MPa
参考答案:C
Natural monopolies exist because they can produce at lower costs with greater output, which means there are economies of scale. Which of the following industries is typically a natural monopoly()
A. Technology.
B. Utilities.
C. Oil.
机动车不得安装影响交通技术监控设备正常使用的装置。