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单选题
Which of the following statements concerning the water tube and fire tube boilers is not true?()
A

natural circulation of the water in the water tube boiler is better than that in the fire tube boiler

B

for the same output the water tube boiler will carry less mass of water compared with the fire tube boiler

C

the water tube boiler will cost shorter time for steam raising

D

the water tube boiler require lower skill in operating and maintaining


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