Any carbon built up on surfaces must be washed away by （） additives and held in suspension by a （） additive.

A、dispersant；detergent

B、detergent；dispersant

C、dispersant；dispersant

D、detergent；detergent

Most marine biological sewage treatment plants consist of all the following statements except （）.

A、aeration tanks

B、settling tanks

C、disinfection agent

D、anaerobic bacteria

Moisture in a D-Cmotor would cause （）.

A、short circuit

B、speed up

C、slow down

D、hunting

Which of the routine maintenance procedures listed is required for starting air receivers?（）

A、over-speeding

B、overload

C、low exhaust temperature

D、high crankcase pressure

The average pressure exerted on piston during each power stroke is termed（）

A、indicated horsepower

B、mean effective pressure

C、exhaust back pressure

D、compression pressure

Most conducting materials such as copper, aluminum, iron, nickel, and tungsten （）.

A、increase in resistance with increased temperature

B、increase in resistance with decreased temperature

C、decrease in resistance with increased temperature

D、increase in conductance with increased temperature