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

<ins id="y7hzc"><xmp id="y7hzc"><pre id="y7hzc"></pre></xmp></ins>

<dl id="y7hzc"><acronym id="y7hzc"><code id="y7hzc"></code></acronym></dl>

<pre id="y7hzc"><acronym id="y7hzc"></acronym></pre>

<sup id="y7hzc"><small id="y7hzc"><div id="y7hzc"></div></small></sup>

單項選擇題

The discharge flow of a reciprocating pump is （）.

A.steady
B.in pulsation
C.continuous
D.large

你可能感興趣的試題

單項選擇題

A centrifugal pump produces the required pressure energy by means of a rotating （） provided with vanes.

A.propeller
B.impeller
C.circumference
D.screw

單項選擇題

The pressure head of a pump is given in the unit of （）.

A.kg
B.MPa
C.meter fluid column
D.None of the above is true