对雷电保护等级为特级的通信导航监视设施，其引下线平均水平间距应不大于（）米。
A、3
B、6
C、9
D、12
参考答案：D
However, at times this balance in nature is disturbed, _______ a number of possibly unforeseen effects.
A．resulting from
B．resulting in
C．having resulted from
D．having resulted in
对变压器有载装置的调压次数是如何规定的？
