● 网络营销强调 （34） 的参与并满足其个性化需求，以此实现企业的经营目标（34）A．经营者 B．供应商 C

A.lower than

B.higher than

C.below

D.equal to

A.lower than

B.higher than

C.as much as

D.the same as

Black smoke coming from a boiler can be caused by _____.

A.low water level

B.high water level

C.excessively high fuel pressure

D.low oil temperature

When steam is being raised on a boiler, the water level will normally _____.

A.drop as the boiler warms up

B.rise as the boiler warms up

C.remain unchanged until the boiler is hot enough

D.rise and fall with the steam demand

A.take no measures

B.extinguish the fire as soon as possible

C.feed water to the boiler

D.open the blow down valve

A feed pump for an auxiliary boiler might lose suction if the _____.

A.boiler water level is low

B.feedwater is too hot

C.boiler steam demand is low

D.feedwater is too cold

The rate of heat transfer in a water-tube auxiliary boiler can be increased by .

A.operating the boiler at less than normal water level

B.installing fins on the firesides of water-tubes

C.increasing the amount of excess air to the burners

D.treating the boiler water with chemical oxygen scavengers

A.natural circulation of the water in the water tube boiler is better than that in the fire tube boiler

B.for the same output the water tube boiler will carry less mass of water compared with the fire tube boiler

C.the water tube boiler will cost shorter time for steam raising

D.the water tube boiler require lower skill in operating and maintaining

The water level in a steaming auxiliary boiler will always _____.

A.rise when the steam pressure is increased

B.remain constant as long as the feed pump operates

C.fall when the steam pressure is decreased

D.vary as the steam demand changes

A distorted furnace in a fire-tube auxiliary boiler may be the result of .

A.firing for extended periods in the low fire mode

B.overheating, due to waterside deposits

C.varying the water level above the crown sheet

D.carrying excessive alkalinity in the boiler water