无码高清视频|成人自拍视频|欧美成人午夜无码A片秀色直播|草美女视频网站|美女被操网站在线观看

<em id="anbor"></em>

<pre id="anbor"><strong id="anbor"></strong></pre>

單項選擇題

High-speed rotating in a centrifugal purifier can produce a force （） larger than the force of gravity.

A.many thousand times
B.between times
C.one time
D.at times

你可能感興趣的試題

單項選擇題

Here some oil in the oily water separator, as a result of its lower （）, will separate and rise into the oil collection space.

A.temperature
B.viscosity
C.density
D.velocity

單項選擇題

Heat energy is a source of power, but （） will cause damage to the engine.

A.excessive heat
B.insufficient heat
C.effective cooling
D.high output