Universal motors will operate on AC or DC current, and are generally found in （）

A . blow out coils B . governor relay C . under voltage trips D . reverse current tri

A . If the file exists it will be opened for editing. If the file does not exist an error message will be displayed. B . If the file exists it will be opened for editing. If the file does not exist a new file with the name file.out will be created and opened for editing. C . If the file exists an error message will be displayed. If the file does not exist a new file with the name file.out will be created and opened for editing. D . If the file exists the operator will be asked whether to open the file or overwrite the file. If the file does not exist a new file with the name file.out will be created and opened for editing.

A .  New York B .  Montreal C .  Quebec D .  San Francisco E .  Seattle F .  Vancouver

A . mv /home/operator . B . mv /home/operator/* . C . mv /home/operator ../.. D . mv /home/operator/all ../home/operator

A . （1）and（2） B . （1），（2）and（3） C . （1）and（3） D . （2）and（3）

A . in order to B . because of C . so that D . so as to

A . lift B . put C . take D . hold

A . temperature rise B . input kilowatts C . horsepower D . operating voltage

A . How long B . How length C . How many times D . How many shift

A . three balls in a vertical line B . two balls in a vertical line C . one ball near the foremast and one ball at each fore yard D . one diamond near the foremast head and one ball at each fore yard

A . straight B . to port C . to starboard D . None of the above

A . New York B . Montreal C . Quebec D . San Francisco E . Seattle F . Vancouver

A . It will respond only to interrogation by 9-Ghz radar signals B . A SART will normally respond to interrogation from a searching vessel's radar if the radar antenna is at least 15 meters high C . A SART will normally respond to interrogation from a searching aircraft's radar if the radar's output power is at least 10，000 watts and the aircraft is at a height of 3000 feet and within 30 nautical miles D . All of the above

A . higher speed required B . flywheel-effect C . lower starting temperatures D . higher compression pressure

A、an immediate crankcase explosion B、oil contamination in the compressed air C、a decrease in compressor capacity D、no immediate loss of the compressed air capacity

A . The colder seawater passing through the condenser tube bundles of the various stages increases evaporator vacuum B . The amount of heated feed water discharged from the feed water heater after cndenser is increased C . Fewer non-condensable gases are created by the flow of colder seawater D . More seawater is allowed to pass through the flint stage overflow weir

A . under heavy loads B . during hot gas defrost C . under light loads D . during starting conditio

A . Closing of the solenoid valve B . Closing of the expansion valve C . An increase in the suction pressure D . Decreasing the suction pressure

A . double frequencies B . single frequency C . dedicated frequency D . multiple frequencie

A . moisture emulsification of the bearing grease B . insufficient circulation and overheating of the bearing C . proper grease circulation to cool the bearing D . sliding friction between balls and race

A . be clear B . be blue C . be light green D . show bubble

A . Low voltage protection circuit B . Non-renewable link fuse C . Renewable link fuse D . Low voltage release circuit

A . cast B . put C . hold D . let out