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單項選擇題Strainers, sometimes called （）, are devices designed to prevent the passage of unwanted solids into or further along a system.

A.dampers
B.filters
C.stopper circuits
D.separators

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1.單項選擇題A(n) （） is a special type of valve which prevents the passage of steam but allows condensate to pass.

A.check valve
B.non-return valve
C.steam trap
D.quick closing trap

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2.單項選擇題Fuel oil tanks must be fitted with （） that can be closed rapidly and remotely in the event of an emergency such as a fire.

A.stop valves
B.non-return valves
C.quick closing valves
D.relief valves

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3.單項選擇題A more sophisticated pressure reducing valve incorporates a pilot valve which controls the fluid above the valve operating piston in response to downstream pressureThe bold and italic word “which” means （）.

A.a pressure reducing valve
B.a pilot valve
C.an operating piston
D.downstream pressure

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4.單項選擇題In its simplest form the pressure reducing valve is opened or closed by （） which is balanced by the downstream pressure acting on a diaphragm.

A.adjusting a nut
B.a pre-tensioned spring
C.any spring
D.upstream pressure

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5.單項選擇題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

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