某产品划分为四个功能区，采用环比评分法得到的功能暂定重要性系数见表9-10，则功能区F，的重要性系数为()。
A. 0．49
B. 0．32
C. 0．16
D. 0．05
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High firing pressures and low exhaust temperature in a diesel engine may resultfrom().
A. decreased piston to cylinder head clearance
B. increased exhaust system back pressure
C. early fuel injection timing
D. low scavenge air temperature
(piston area)×(piston stroke)×(numbers of the cylinders)=engine().
A. brake horsepower
B. displacement
C. cylinder volume
D. cylinder clearance
某产品的实际成本是2000元，目标成本是1800元，其各个部件的功能指数及成本指数见表9-7，部件A、B、C的成本改进期望值应分别为()元。
A. 60，60，80
B. 74，56，70
C. 200，20，－20
D. 140，－40，－100
If the coolant temperature of a closed cooling water system for a diesel enginegradually increases, the trouble usually is().
A. a broken shaft on the freshwater pump
B. an excessive accumulation of scale in the heat exchanger
C. an incorrect thermostatic element operating range
D. lube oil in the cooling water
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