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單項(xiàng)選擇題

A （）, sometimes called filters, is a device designed to prevent the passage of unwanted solids into the system.

A.steam trap
B.check valve
C.separator
D.strainer

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單項(xiàng)選擇題

To maintain the down stream pressure within defined limits over a range of flow and despite any changes in supply pressure, （） is fitted.

A.a check valve
B.a gate valve
C.a pressure reducing valve
D.a quick closing valve

單項(xiàng)選擇題

The main objective of the SOLAS Convention is to specify （） for the construction, equipment and operation of ships, compatible their safety.

A.at most references
B.at least references
C.maximum standards
D.minimum standards

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