下列哪些情况应考虑更换重力环（）。Ⅰ.排查口跑油Ⅱ.换用不同品种的燃油Ⅲ.分油机由并联使用转成串联

ns, the design of the engine and the type of fuel to be burned.

A.commercially available

B.commercially

C.commercial available

D.commerce available

.

A.size of the heat sink

B.temperature difference between the regions

C.size of the heat source

D.total heat of the system

ressure will be_____at slow speed.

A.a little lower

B.a little higher

C.too low

D.exactly the same

泵的管路特性曲线陡表明________。

A.吸、排液面间的压力差大

B.管路漏泄多

C.吸、排液面间的高度差大

D.管路流动阻力损失大

下列泵中主要转动部件不需要特殊方法平衡轴向力的是________。

A.单吸离心泵

B.螺杆泵

C.单侧流道开式旋涡泵

D.双吸离心泵

l axis.

A.windlasses

B.drums

C.capstans

D.warp ends

The ship should be operated by a company which is issued a(an)______relevant to ship.

A.ISM

B.DOC

C.SMC

D.PSC

新型中速柴油机一般都采用（）。

A.倒挂式主轴承、不设机座

B.倒挂式主轴承、设机座

C.正置式主轴承、不设机座

D.正置式主轴承、设机座

water.

A.starting

B.stopping

C.to start

D.to stop

曲轴箱爆炸的决定性因素是（）。

A.油雾浓度达到爆炸限

B.主机转速太高

C.主轴承损坏

D.轴承发热，活塞环漏气