对落地的高压线应离开落地点（），以免跨步电压伤人。
A.2～3m
B.3～5m
C.5～8m
D.8～10m
参考答案：D
列举你所知道的事物对立面相互转化的成语或故事。
__________________________________________________________________
At the railway station，he waved goodbye to his friend until the train was ________.
A．out of sight
B．out of reach
C．out of order
D．out of place
