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

<pre id="gjp9s"><acronym id="gjp9s"></acronym></pre><pre id="gjp9s"><strong id="gjp9s"></strong></pre>

單項選擇題

A shallow dish positioned at the normal water level is connected to the（）This enables the blowing down or removal of scum and impurities from the water surface.

A.main stern stop valve
B.auxiliary steam stop valve
C.scum valve
D.blow down valve

你可能感興趣的試題

單項選擇題

The（）enables water to be blow down or emptied from the boilerIt may be used when partially or completely emptying the boiler.

A.main stem stop valve
B.auxiliary steam stop valve
C.feed check or control valve
D.blow down valve

單項選擇題

The（） is fitted in pair one is the main valve, the other the auxiliary or standby.

A.main stem stop valve
B.auxiliary steam stop valve
C.feed check or control valve
D.blow down valve

<ruby id="9yh48"><output id="9yh48"></output></ruby>

<pre id="9yh48"><strong id="9yh48"></strong></pre>