题目内容
（请给出正确答案）
Tire pressure changes .
A．in different weather conditions
B．in different road condition
C．when wide-track tires are used
D．when narrow-track tires are used
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A.Total Productive Maintenance
B.Plan Maintain
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Task 2
Directions: This task is the same as Task 1. The 5 questions or unfinished statements are numbered 41 through 45.
Once it was considered good to keep the car engine idle a minute or two following cold stars. Today, with modern technology, the opposite is true. An engine operating under road conditions will warm up faster and run more efficiently than one that is idling. Idling just burns gas (on average, about a gallon an hour).
When you have a full tank of gas, park the car facing downhill is possible: this will prevent any gas from coming out of the tank. Parking in areas of less or no sunlight helps prevent the gas from steaming that would occur if you parked in the hot sun. Your car will stay cooler, too, and that means less gas consuming work for the air conditioner once the engine is started.
Stay away from wide-track tires if you want top mileage (耗油1升行驶的英里里程). Narrow-track tires produce less friction and thus rolling resistance. The same effect is achieved by adding three to five pounds above recommended pressure to each tire; while this won't noticeably affect your car's sliding quality, it will increase tire life and gas mileage.
Check tire pressure often, especially when the weather turns cold. The difference between winter and summer tire pressure can be as much as eight pounds. This could cost you two miles per gallon.
The main purpose of the passage is .
A．to tell us how expert drivers try to save gas
B．to tell us how to drive a car properly
C．to tell us how to make a car run smoothly
D．to tell us how to make your car consume less gas
If possible,when you have a full tank of gas,park the car facing downhill,as this will prevent any gas from leaking out of the tank.Parking in areas of little or no sunlight helps prevent evaporation(蒸发)of the gas which would occur if you parked in the hot sun.Your car will stay cooler,too,and this means less gas is consumed for the air conditioner once the engine is started.
Stay away from wide-track tires if you want top mileage for your dollar.Narrow-track tires produce less friction and thus rolling resistance.The same effect is achieved by adding three to five pounds above recommended pressure to each tire while this won't noticeably affect your car's mobility,it will increase the life of your tires and gas mileage.
Check tire pressure often,especially when the weather turns cold.The difference between winter and summer tire pressure can be as much as eight pounds.This could cost you two miles per gallon.
1.The main purpose of the passage is to tell us（）.
A.how expert drivers try to save gas
B.how to drive a car properly
C.how to make a car run smoothly
D.how to make your car consume less gas
2.According to the passage,keeping the engine run idly（）.
A.will just waste gas
B.will warm it up more quickly
C.will make it work more efficiently
D.is necessary in cold weather
3.Parking your car in a cool place（）.
A.will take it longer to warm up the engine
B.means less gas consumption for the air conditioner
C.prevent any gas from coming out of the tank
D.helps start your car more easily
4.Wide-track tires（）.
A.won't noticeably affect your car's sliding quality
B.can increase tire life
C.will increase rolling resistance
D.helps attain top gas mileage
5.Tire pressure changes（）.
A.when wide-track tires are used
B.when narrow-track tires are used
C.in different weather conditions
D.in different road conditions
Animals on the Move
It looked like a scene from “Jaws” but without the dramatic music. A huge shark was lowly swimming through the water, its tail swinging back and forth like the pendulum of a clock.
Suddenly sensitive nerve ending in the sharks skin picked up vibrations of a struggling fish. The shark was immediately transformed into a deadly, efficient machine of death. With muscles taut, the shark knifed through the water at a rapid speed. In a flash the shark caught its victim, a large fish, in its powerful jaws. Then, jerking its head back and forth, the shark tore huge chunks of flesh from its victim and swallowed them. Soon the action was over.
Moving to Survive
In pursuing its prey, the shark demonstrated in a dramatic way the important role of movement, or locomotion, in animals.
Like the shark, most animals use movement to find food. They also use locomotion to escape enemies, find a mate, and explore new territories. The methods of locomotion include crawling, hopping, slithering, flying, swimming, or walking.
Humans have the added advantage of using their various inventions to move about in just about any kind of environment. Automobiles, rockets, and submarines transport humans from deep oceans to as far away as the moon. However, for other animals movement came about naturally through millions of years of evolution. One of the most successful examples of animal locomotion is that of the shark. Its ability to quickly zero in on its prey has always impressed scientists. But it took a detailed study by Duke University marine biologists S. A． Wainwright, F． Vosburgh, and J. H. Hebrank to find out how the sharks did it. In their study the scientists observed sharks swimming in a tank at Marine land in Saint Augustine, Fla. Movies were taken of the sharks’ movements and analyzed. Studies were also made of shark skin and muscle.
Skin Is the Key
The biologists discovered that the skin of the shark is the key to the animal’s high efficiency in swimming through the water. The skin contains many fibers that crisscross like the inside of a belted radial tire. The fibers are called collagen fibers. These fibers can either store or release large amounts of energy depending on whether the fibers are relaxed or taut. When the fibers are stretched, energy is stored in them the way energy is stored in the string of a bow when pulled tight. When the energy is released, the fibers become relaxed.
The Duke University biologists have found that the greatest stretching occurs where the shark bends its body while swimming. During the body’s back and forth motion, fibers along the outside part of the bending body stretch greatly. Much potential energy is stored in the fibers. This energy is released when the shark’s body snaps back the other way.
As energy is alternately stored and released on both sides of the animal’s body, the tail whips strongly back and forth. This whip-like action propels the animal through the water like a living bullet.
Source of Energy
What causes the fibers to store so much energy？ In finding the answer the Duke University scientists learned that the sharks similarity to a belted radial tire doesnt stop with the skin. Just as a radial tire is inflated by pressure, so, too, is the area just under the sharks collagen “radials”. Instead of air pressure, however, the pressure in the shark may be due to the force of the blood pressing on the collagen fibers.
When the shark swims slowly, the pressure on the fibers is relatively low. The fibers are more relaxed, and the shark is able to bend its body at sharp angles. The animal swims this way when looking around for food or just swimming. However, when the shark detects an important food source, some fantastic involuntary changes take place.
The pressure inside the animal may increase by 10 times. This pressure change greatly stretches the fib
A．to find food
B．to avoid being chased by its enemies
C．to find a new place to live
D．to show its braveness
Which of the following gives a general idea of how the noise-killing system works？
A．By producing pressure waves going in the opposite direction.
B．By mixing high frequency sound waves with low frequency sound waves.
C．By mixing new sound waves with the noise and sending them out together.
D．By making copies of tire unwanted sound waves and letting them out a little later.
His wife has been ______ a lot of pressure on him to change his job.
A．taking
B．exerting
C．giving
D．pushing
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