单项选择题
A.casting interlocking components
B.welding plates to form sections for assembly
C.forging integral components
D.case hardening integral components
单项选择题 Prior to lighting off a cold automatically fired auxiliary boiler, you should （）.
单项选择题 Which of the following statements describes the function of an expansion tank in a diesel engine cooling system?（）
单项选择题 To minimize corrosion, fuel oil strainer disks, spacers and scraper blades are made of （）.