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A low in a marine weather report is an air pressure system the pressure at the center of which is ______.
A.the highest over the area
B.the lowest over the area
C.higher than 1013 HPA
D.lower than 1013 HPA
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更多 “ A low in a marine weather report is an air pressure system the pressure at the center of which is ______.A.the highest over the areaB.the lowest over the areaC.higher than 1013 HPAD.lower than 1013 HPA ” 相关考题
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Forces other than damaging winds are also at work inside tornadoes (龙卷风) . Sometimes,as the wind passes a house, the walls and ceiling burst apart as if a bomb had gone off inside. This explosion is caused by the low air pressure at the center of a tornado.The pressure at the center of a tornado is usually 13 pounds per square inch. However,inside the house the air pressure is normal, about 15 pounds per square inch.The difference of 2 pounds per square inch between the inside and outside pressure may not seem like much. But suppose a tornado passes over a small building that measures 20 by 10 by feet. On each square inch of the building, there is 2 pounds of pressure from the insidethat is not balanced by air pressure outside the building. On the ceiling, that adds up to an unbalanced pressure of 57600 pounds. The pressure of the four walls adds up to 172800 pounds.If windows are open in the building, some of the inside air will rush out through them.This will balance the pressure inside and outside the building.But if the windows are shut tightly, the huge inside pressure may cause the building to burst.Unfortunately, heavy rain often occurs in the storms that later produce tornadoes,so people often shut their windows. This may cause far worse damage later.21、 What did the paragraph before this passage most probably discuss?A、 Measuring rainfall from a stormB、 The kinds of damage caused by explosionsC、 The powerful winds of tornadoes22、 Which of the following is the main topic of the passage?A、 How tornadoes can be preventedB、 When tornadoes usually occurC、 Why tornadoes cause so much damage23、 Tornadoes can destroy buildings because the()A、 force of a tornado increases the air pressure in a buildingB、 air pressure inside a tornado is less than the air pressure inside a buildingC、 air pressure at the center of a tornado is over 172000 pounds24、 What is the difference per square inch between the air pressure inside a building and the air pressure inside a tornado?A、 2 poundsB、 13 poundsC、 15 pounds25、 What would happen if the windows are shut tightly in the stormy weather?A、 Tornadoes may be formedB、 The house may be apartC、 There may not be any pressure inside the building
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Of the following, which one is not a term of Marine Weather Bulletin?______.A.Complex lowB.DepressionC.High pressureD.Ambient pressure
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The circulation around a low pressure center in the Northern Hemisphere is ______.A.counterclockwiseB.variableC.clockwiseD.Anticyclonic
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Low compressor head pressure in a refrigeration system can be caused by ___.A.insufficient condenser cooling waterB.excessive condenser cooling waterC.air in the refrigeration systemD.excessive refrigerant in the system
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A decrease in barometric pressure is associated with all of the following except ______.A.rising warm airB.proximity to a low pressure areaC.inward spiraling circulationD.clear dry weather
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A single barometric pressure reading of 28.60 indicates ______.A.rapidly improving weatherB.deteriorating weatherC.a severe low pressure systemD.fair weather and calm
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Which general weather conditions should you expect to find in a low pressure system ________．A.Fair weatherB.Precipitation and cloudinessC.Scattered clouds at high elevationsD.Gradual clearing and cooler temperatures
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If a weather bulletin shows the center of a low pressure system to be 100 miles due east of you, what winds can you expect in the Southern Hemisphere? ______.A.South-southwesterlyB.North-northwesterlyC.South-southeasterlyD.North-northeasterly
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If your weather bulletin shows the center of a low pressure area to be 100 miles due east of your position, what winds can you expect in the Northern Hemisphere?______.A.East to northeastB.East to southeastC.North to northwestD.South to southeast
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单选题A marine diesel engine is started by（）A
supplying high pressure oil into a hydraulic motorB
supplying high temperature air into the cylinderC
supplying high pressure air into the cylinderD
electrical igniting
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单选题In an air conditioning system, low head pressure associated with a reciprocating compressor can be the result of （）A
broken valve springsB
tight drive beltsC
high line voltageD
air in the system
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单选题Compared to a low pressure system，generally the air in a high is（）.A
warmer，less dense，and less stableB
cool，more dense，and drierC
muggy and cloudyD
extremely moist with high relative humidity
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单选题Cast irons weakness in tension and under shock loading limits its use to low pressure steam, air, oil and low speed water fittingsThe above sentence, most probably means （）.A
cast iron has weaknessB
cast iron can stand up shock loadingC
cast iron fittings are only suitable in low pressure situationD
east iron fittings are not suitable in low pressure situation
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单选题A decrease in barometric pressure is associated with all of the following except（）.A
rising warm airB
proximity to a low pressure areaC
inward spiraling circulationD
clear dry weather
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单选题The loss of the diesel engine cylinder air charge through leaky valves, piston rings, worn or scored liners, would be indicated by which of the following sets of conditions?（）A
Low compression pressure and high exhaust temperatureB
Low firing pressure and high exhaust temperatureC
Low compression pressure and low exhaust temperatureD
Low firing pressure and low exhaust temperature
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单选题A single barometric pressure reading of 28.60 indicates（）.A
rapidly improving weatherB
deteriorating weatherC
a severe low pressure systemD
fair weather and calm
考题
单选题Which general weather conditions should you expect to find in a low pressure system（）.A
Fair weatherB
Precipitation and cloudinessC
Scattered clouds at high elevationsD
Gradual clearing and cooler temperatures
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单选题The compressor in an air-cooled condensing refrigeration system is short cycling on the high pressure cutout switch（）A
system is overcharged with refrigerantB
system is low on refrigerantC
discharge valves are leaking excessivelyD
discharge valves are leaking slightly
考题
单选题If your weather bulletin shows the center of a low pressure area to be 100 miles due east of your position，what winds can you expect in the Northern Hemisphere?（）.A
East to northeastB
East to southeastC
North to northwestD
South to southeast
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单选题Low pressure air is usually taken through （） or pressure regulators to a low pressure reservoir supplying a ring main through driers.A
globe valvesB
butterfly valvesC
gate valvesD
reducing valves
考题
单选题The greater the pressure difference between a high and a low pressure center，the（）.A
dryer the air mass will beB
cooler the temperature will beC
greater the force of the wind will beD
warmer the temperature will be
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单选题The purpose of the refrigeration system low pressure cutout switch is to （）A
protect the compressor from liquid flood backB
protect the compressor from low discharge pressureC
start and stop the compressor upon system demandD
start the compressor after a drop in the evaporator pressure
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单选题An un-loader is installed on an air compressor to （）.A
bypass the high pressure stage to the low pressure stage on 100% of the air compressors in serviceB
prevent excessive inter-stage pressure buildupC
control compressor discharge pressureD
remove all but the frictional load during starting
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单选题Pump up the starting air reservoirs to their maximum pressure and （）the air reservoirs and air system.A
openB
closeC
drainD
vent
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单选题An indication of a diesel engine air intake being partially clogged, is （）.A
low firing pressure and low exhaust temperaturesB
low firing pressure and normal exhaust temperaturesC
high firing pressure and low exhaust temperaturesD
high firing pressure and high exhaust temperatures
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单选题Excessively low air pressure occurring in the intercooler of a reciprocating air compressor is caused by（）.A
leaky discharge valves on the LP cylinderB
leaky discharge valves on the HP cylinderC
insufficient intercooler coolingD
low ambient air pressure
考题
单选题The circulation around a low pressure center in the Northern Hemisphere is（）.A
counterclockwiseB
variableC
clockwiseD
anticyclonic
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