A.sliding blockB.pintleC.reaction ringD.tilting box or ……

单项选择题Badly leaking refrigeration compressor discharge valves will cause（）.

A.overfeeding of the expansion valve
B.damage to the condenser
C.constant running of the compressor
D.flooding of the receiver

单项选择题Mechanical energy in transition is referred to as （）.

A.horsepower
B.work
C.heat
D.velocity

单项选择题If you change from a low pour point lubricant to a high pour point lubricant in a refrigeration system, （）.

A.compressor lubrication will be improved
B.oil will not leave the crankcase
C.compressor valves will be damaged
D.oil may congeal in the evaporator

单项选择题When a vessel is in dry-dock, the vessel’s engineers should （）.

A.examine the condition of the propeller
B.chip and paint all hull protection zincs
C.install new docking plugs in all cofferdams
D.inspect the hull for hogging or sagging

单项选择题Air line lubricators are used in compressed air systems to lubricate （）.

A.the suction and discharge valves
B.tools and equipment served by compressed air
C.air line reducing valves
D.all of the above