The frequency of an alternator at a given RPM is determined by the ______.
A. number of turns of wire in the armature(电枢) coil
B. number of magnetic poles
C. strength of the magnets used
D. output voltage
Stern tube and strut(支柱) bearings lined with hardwood or rubber composition materials are lubricated with______.
A. saltwater
B. graphite(石墨)
C. light lubricating oil
D. heavy lubricating oil
This certificate was issued________the provisions.
A. according to
B. with
C. for
D. below
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