单项选择题
Which of the listed devices could be used as a substitute for a ring grooving tool?（）
A.Steel brush B.Fine emery cloth or steel wool C.A section of the removed compression ring D.A case hardened scraper
单项选择题 In which of the scavenging methods listed will the exhaust valve be located in the cylinder head?（）
单项选择题 When using a fuel with a higher than normal sulfur content in an auxiliary diesel engine, you should（）
单项选择题 When fuel is injected late into a diesel engine cylinder,（）.
