97免费在线观看视频,亚洲综合自拍网,黄色毛片免费观看,热久久综合网,免费看日产一区二区三区狠狠操av,久久久涩涩涩,在线精品免费视频,人人插天天干,久久91精品国产91久久

<address id="970tk"><form id="970tk"><dfn id="970tk"></dfn></form></address>

<pre id="970tk"></pre>

<ruby id="970tk"><xmp id="970tk"></xmp></ruby>

單項選擇題

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

你可能感興趣的試題

單項選擇題

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

單項選擇題

Annex IV of MARPOL 73/78 contains regulations for the prevention of （）.

A.pollution by oil
B.pollution by noxious liquid substances carried in bulk
C.pollution by sewage from ships
D.pollution by garbage from ships

<ins id="eejmt"><output id="eejmt"></output></ins>