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

單項(xiàng)選擇題

They understand the （） of automatic sludge discharging of the purifierBut they are not good in practice.

A.principle
B.principal
C.cause
D.case

你可能感興趣的試題

單項(xiàng)選擇題

These piston rings are so badly worn that they must be （）.

A.renewed
B.welded
C.machined
D.chromium-plated

單項(xiàng)選擇題

There should be a lubricating oil （） between the main beatings and the crankshaft.

A.film
B.cap
C.lacquer
D.shell

<pre id="hirwk"><xmp id="hirwk">

<blockquote id="hirwk"></blockquote>