单项选择题
A.safe for becoming rounded B.safe for hot work C.not safe for personnel D.not safe for hot work
Safe welding practice requires （）A.checking the area fo...
单项选择题Safe welding practice requires （）
A.checking the area for items that may catch fire B.that a fire watch be posted C.checking for the explosive gases D.all of the above
Which lubricating oil additive is used in diesel engine...
单项选择题Which lubricating oil additive is used in diesel engines to reduce the tendency for sludge and varnish to form on the engine parts?（）
A.Flash point improvers B.Pour point improvers C.Inhibitors D.Foam suppressors
Which of the following characteristic of lube oil helps...
单项选择题Which of the following characteristic of lube oil helps to reduce the amount of deposits in the piston ring belt during the combustion process in a diesel engine?（）
A.Low viscosity index B.Low carbon forming tendencies C.High film strength D.High non-corrosive qualities
