以下属于地面气象观测资料常规调查项目的是( )。
A．湿球温度 B．时间 C．降水量 D．相对湿度
参考答案：B
_______ a precious diamond necklace for his wife, Martin could hardly afford a tie for himself.
[ ]
A. Having bought
B. Buying
C. Being bought
D. To buy
10BASE-T使用标准的RJ-45接插件与3类或5类非屏蔽双绞线连接网卡与集线器。网卡与集线器之间的双绞线长度最大为______。
A．15m
B．50m
C．100m
D．500m
