A.many thousand times larger than B.the same as C.many thousand times smaller D.none of the above
A.lube oil B.fuel oil C.turbine oil D.grease
Which of the following may hardness of the boiler water cause?() (1) scale formation (2) tube failure (3) corrosion
A.(1)and(2) B.(1)and(3) C.(2)and(3) D.(1),(2)and(3)