相关考题
-
单项选择题
Which of the following materials is a good insulator?（）
A.steel
B.aluminum
C.glass
D.copper -
单项选择题
To protect the rotor of a motor disassembled for maintenance or overhaul, it should be（）
A.suspended by wire slings in one comer of the shop
B.wrapped in several layers of heavy paper or carboard
C.supported by flat wood blocks on the workbench
D.returned to the frame as soon as the bearings are removed -
单项选择题
When paralleled, AC generators must have the same （）
A.frequency
B.number of phases
C.phase rotation
D.All of the above
