單項選擇題Which of the following precautions must be taken if an electric immersion heater is used to keep the coolant in a diesel engine warm during the time the engine is secured?（）

A.The coolant temperature must be maintained at 180℃
B.The thermostatic bypass valves must be manually opened before the engine is started
C.The pressure cap must be removed while the engine is secured
D.Electrical power to the heater must be secured before the cooling system is drained


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1.單項選擇題Which of the following statements is true regarding the installation of piston rings on two-stroke/cycle, diesel engines as compared to four-stroke/cycle, diesel engines?（）

A.In a two-stroke/cycle engine, the rings run hotter, requiring the end gap to be greater
B.Some provision must be made in a two-stroke/cycle engine to keep the rings from binding in the ports
C.No gap is required to exist between the ends of the ring when cold in a two-stroke/cycle engine, but a small gap is required in a four-stoke/cycle engine
D.The gaps should be staggered on either side of a piston in a two-stroke/cycle engine, while staggering is not necessary in a four-stroke/cycle engine

2.單項選擇題If a crankcase explosion occurs in a diesel engine, which of the listed actions should be taken?（）

A.Open the crankcase immediately to check for damage
B.Apply fire fighting water through the crankcase breather
C.Allow the engine to cool before opening the crankcase
D.Assume that there is no damage to the crankshaft

4.單項選擇題If the turbocharger of a four-stroke/cycle diesel engine fails to operate, which of the following statements best describes the probable effect?（）

A.Intake manifold pressure will be high
B.Intake manifold pressure will be unaffected
C.Exhaust temperatures will be high
D.Exhaust temperatures will be low

5.單項選擇題The best tool to use for removing the carbon ridge at the top of an enginecylinder, prior to removing the piston, is to use（）

A.an electric grinder
B.a metal scraper
C.a reamer
D.a three-wing hone