All of the following operating characteristics are listed on the name-plates of motors used aboard ship except the（）

单项选择题When would you ground an electric hand tool?（）

A.When it is a DC machine
B.When it is an AC machine
C.Any machine that operates on over 100 volts
D.Only when working on wet steel plates

单项选择题The load between two steam-driven alternators operating in parallel may be adjusted by varying （）

A.the speed of the alternators
B.the field strength of the machines
C.the power factor of the alternators
D.steam supply to the prime movers

单项选择题The purpose of the commutator and brushes on a DC generator is to（）

A.change AC to DCcurrent
B.change DC to AC current
C.neutralize a armature reaction
D.carry current to the outside circuit

单项选择题DC generators are classified according to the manner in which（）

A.they are used
B.the field windings are connected to the load
C.the armature circuit is connected to the load
D.the field windings are connected to the armature circuit

单项选择题A circuit that has one wire in contact with the hull of the ship is a（）

A.series circuit
B.grounded circuit
C.short circuit
D.closed circuit