题目内容：
根据下面资料，回答题 Modern AirplanesAirplane Instruments
A．Modern airplanes are complicated machines．Pilots need many gauges (量表) and electronic aids tohelp fly them．The flight deck of a large passenger plane contains many indicator dials and warninglights．One of the most important instruments is the altimeter, which tells the pilot how high the planeis off the ground．The air speed indicator measures the plane's speed．The artificial horizon shows theposition of the plane relative to the horizon．The turn and back indicator shows how much, if at all, theplane is turning and tilting．In dense clouds and fog, a pilot would not always know which way the planeis heading if it weren't for this instrument．A gyrocompass (旋转罗盘) and various radio devices arenecessary for navigation.
B．Most large planes also have an automatic pilot．This is a device operated by a computer．It will fly theplane without the pilots touching the controls．These autopilots can even control takeoffs and landings．The flight deck also contains many gauges and meters that tell the pilot whether the many pieces ofequipment on the plane are operating properly．They measure fuel level, temperatures, cabin pressure,electric current, etc．Indicators show whether the landing gear is up or down．The radio equipment allowsthe pilot to talk to ground controllers and to receive navigation signals．
Airplane Construction
C．Early airplanes were made of wood frames covered by fabric and held in shape by wire．After World War I,airplane designers started to use lightweight metals like aluminum, titanium, and magnesium alloys．Athin skin of metal was riveted into place over metal ribs．Strong epoxy (环氧的) glues are now used forsome joints, instead of rivets．As planes grew in size, they became heavier．More powerful engines were
developed in order to fly the heavier planes.
D．The use of metals brings with it a problem called metal fatigue．Stress and vibration in flight can causemetal parts eventually to break up．Airplanes must be constantly checked for signs of this trouble．Defective parts must be renewed by aircraft maintenance people.
E) Designers test scale models in wind tunnels before the full sized planes are built．Reactions of the modelsto high speed air streams give good indications how full sized planes will react in flight．This approachhelps save a lot of money．It also helps to make airplanes safe.
Airport
F) An airport is a place where airplanes arrive and depart．Passengers leave and arrive on the airplanesand cargo is loaded and unloaded．Large, jet powered airplanes require long runways for takeoffs andlandings．Big terminal buildings are necessary to handle thousands of passengers and their baggage．Verylarge airports usually serve several large cities and cover thousands of acres．Hundreds of planes arriveand depart daily．All this traffic must be carefully controlled to avoid delays and accidents．This is donefrom a control tower．The tower stands high above the ground．Air traffic controllers, inside the tower,must be able to guide airplanes through their takeoffs and landings.
G) Large airports are often like small cities．Many have post offices, banks, hotels, restaurants, and manykinds of shops．Airports have their own fire and police departments, fuel storage tanks, and repair workshops．Some companies even have their shipping warehouses located at airports．One of the largest
airports in the world is in Grapevine, Texas, midway between the cities of Dallas and Fort Worth．Thisairport covers 7,200 hectares (18,000 acres)．Its five terminals can handle the arrivals and departures of90 jumbo jets at the same time．O'Hare International Airport, in Chicago, is the busiest airport in theworld．It handles more than 37 million passengers a year．Small airports that are used only by private
airplanes usually cover 20 to 40 hectares (50 to 100 acres).They do not need all the buildings and servicesof a large airport．The control tower may be just a small room in a building at ground level.
Runways
H) Early planes were light．Early runways were sometimes just level grass fields．Paved runways became necessarywhen airplanes became heavier and faster．Today's big jet planes weigh hundreds of tons．They move alongrunways at speeds of 160 kph (100 mph).When they land, the runways take a lot of pounding and must be made
of concrete or asphalt ( 沥青)．They must have solid foundations and a surface that prevents skidding.
I)Airplanes take off into the wind in order to get better lift．They also land into the wind to have bettercontrol as they slow down．Most airports have runways pointing in different directions．This means thatthere are always runways on which airplanes can go into the wind as they take off and land.
J)Heavily loaded passenger jets need long runways to gather enough speed to leave the ground．Runwaysat some large airports are longer than 3,000m(10, 000 ft)．At night, bright lights line the runways so thatpilots can find them without trouble．A system of flashing guide lights is set up beyond the runway tohelp pilots land safely．
Control Towers
K) People who work in control towers are called air traffic controllers．They direct the movements of allplanes on the ground and in the air by keeping track of them on large radar screens．Air traffic controllerstell a pilot, by radio, when and where to taxi or pilot the plane down the runway.
L) Electronic equipment is used to guide airplanes．Long range radar is used to keep track of planes faraway from the airport．This radar is called Ground Control Approach (GCA..When the airplane getswithin a few miles of the runway, the air traffic controller begins to use Precision Approach Radar (PAR)．This allows the controller to guide the airplane to within 0.4km (0.25mi) of the runway．At that point, thepilot completes the landing．Another electronic aid used in bad weather is the Instrument Landing System(ILS)．In this system, radio transmitters located near the runway send guidance signals to the airplane.
These signals tell the pilot how to steer the plane for the final approach to the runways．Today, there arealso electronic "microwave" landing systems (MLS) that can land the plane fully automatically.
Terminal Buildings
M) Terminal buildings vary in size and shape．Most of them are quite large．More than 228 million peoplefly on the airlines in America every year．Every passenger must pass through terminals．Long, covered walkways lead from the center of some terminals to the gates where airplanes are boarded．At some airports, buses are used to transport passengers to their airplanes．Passengers arriving from anothercountry must pass through customs and passport control．Customs officials check the incoming baggagefor taxable items．They also check passengers to be sure no forbidden items are brought into the country．Passport officials check the passports of passengers for personal identification.
N) Passengers are not allowed to bring guns, knives, or other weapons onto a passenger airplane．Beforeboarding, they must walk through a detector which triggers a special signal if they are carrying anythingmade of metal．Luggage is also examined for weapons．This is done to ensure the safety of the passengers.
In bad weather, the radio transmitters near the runway send signals informing the pilot how to steer theplane for the final approach to the runways.
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