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單項選擇題

Before welding is permitted on a fuel tank, it must be certified or declared （）

A.safe for becoming rounded
B.safe for hot work
C.not safe for personnel
D.not safe for hot work

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單項選擇題

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

單項選擇題

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

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