可用性测试

A. 清扫平台宽度
B. 安全平台宽度
C. 矿石贮量

A network that is restricted.to A single building ,A group of buildings, or even A single room.
B. A network that encompasses an entire city or metropolitanared and connects multiple LANs.
C. A network that connects client devices wirelessly using radio waves.
D. A network that crosses metropolitan, regional, or national boundaries.