99色精品-9色在线-99色在线-99色视频国产欧美日产一区二区三区_亚洲精品亚洲人成在线观看_四虎在线精品永久观看_免费一级a一片久久精

<thead id="4kw2k"><cite id="4kw2k"></cite></thead>

<ruby id="4kw2k"><xmp id="4kw2k"></xmp></ruby>

<menu id="4kw2k"><strong id="4kw2k"></strong></menu>

單項(xiàng)選擇題

The lowest ring of a piston is （）.

A.a coil spring
B.a sealing ring
C.an oil distributor ring
D.main seal ring

你可能感興趣的試題

單項(xiàng)選擇題

The lower end of each piston rod is reduced in diameter to fit a bore in （）.

A.the crosshead
B.the journals of the crosshead
C.the crosshead shoes
D.the guides

單項(xiàng)選擇題

The lower end of each piston rod is reduced in diameter to fit a bore in （）, this being secured to the piston rod by a nut.

A.the crank-web
B.the connecting rod
C.the main bearing
D.the cross-head

<em id="qj3ab"></em>