【简答题】七大洲中 ,面积最大的是_________,最小的是_________,四大洋中,面积最大的是_________,最小的是_________。
【判断题】杂散电流的防护设计应采取“以堵为主,以排为辅,防排结合,加强检测”的原则。
【简答题】在世界四大洋中,面积最大的是______洋,面积最小的是_____洋。
【简答题】七大洲中,面积最大的是______,四大洋中,面积最小的是______.
【简答题】出现系统故障时,最有效的操作方式是____。
【简答题】在直流牵引供电的系统中,对杂散电流的总防护原则是:以防为主,以排为辅、 、加强监测。
【单选题】听力原文: Years ago before there were refrigerators, an icehouse was a building used for storing ice. The first teahouses were in the cellars of farmhouses. Pieces of ice, mixed with snow and meadow grass...
A.
Separate houses were built for storing ice.
B.
Double walls were built in icehouses to keep cool.
C.
Blocks of ice were packed with hay in icehouses.
D.
ice was put into icehouses in winter.