WHAT IS THE MAIN THEME OF THIS PASSAGE

38: What is the main theme of this passage?

A. how people should use fast food B. possible hazards of fast food to health

C. why Americans get more fast food. D. when to use fast food for your health

Read the following passage and mark the correct answer to each of the following questions.

THE SCIENCE OF AVIATION

Captain John Paul Stapp, already a medical doctor, began his scientific career in the 1940s studying the

negative effects of high-altitude flight, issues absolutely critical to the future of aviation. How could men

survive these conditions? The problem of the bends, the deadly formation of bubbles in the bloodstream, proved

the toughest, but after 65 hours in the air, Stapp found an answer. If a pilot breathed pure oxygen for 30 minutes

prior to take-off, symptoms could be avoided entirely. This was an enormous breakthrough. The sky now truly

was the limit. The discovery pushed Stapp to the forefront of the Aero Med Lab and he abandoned his plans to

become a pediatrician, instead deciding to dedicate his life to research. The Lab's mandate, to study medical and

safety issues in aviation, was a perfect match for his talents. It was the premiere facility in the world for the new

science of biomechanics.

Stapp was assigned the Lab's most important research project: human deceleration. This was the study of the

human body's ability to withstand G forces, the force of gravity, when bailing out of an aircraft. In April 1947,

Stapp travelled to Los Angeles to view the 'human decelerator', a rocket sled designed to run along a special

track and then come to a halt with the aid of 45 sets of normal hydraulic brakes, which slowed it from 150 miles

per hour to half of that speed in one fifth of a second. When it did, G forces would be produced equivalent to

those experienced in an airplane crash. The sled was called the 'Gee Whiz'. Built out of welded tubes, it was

designed to withstand 100 Gs of force, way beyond the 18 Gs that accepted theory of the time thought

survivable. Early tests were conducted using a dummy, but Stapp soon insisted that conditions were right to use

himself as a human guinea pig.

Exercising a modicum of caution on the first ride in December 1947, Stapp used only one rocket. The Gee

Whiz barely reached 90 miles an hour, and the deceleration was only about 10 Gs. So Stapp began to increase

the number of rockets, and by August 1948, he had completed 16 runs, surviving not just 18 Gs but a bone-

jarring 35 Gs.

Battered though he was by the tests, Stapp was reluctant to allow anyone else to ride the Gee Whiz. He feared

that if certain people, especially test pilots, were used, their hotheadedness might produce a disaster. Volunteers

made some runs, but whenever a new approach was developed, Stapp was his own one and only choice as test

subject. There was one obvious benefit: Stapp could write extremely accurate physiological and psychological

reports concerning the effects of his experiments.

Yet while the Gee Whiz allowed Stapp to answer the existing deceleration questions, new ones emerged.

What could be done to help pilots ejecting from supersonic aircraft to survive? Stapp set out to find the answer

on a new sled called Sonic Wind No. 1, which could travel at 750 miles per hour, and withstand an astonishing

150 Gs. In January 1954, Stapp embarked on a series of runs leading to his 29

and final ride, which took him to

above the speed of sound, protected only by a helmet and visor. And when the sled stopped, in a mere 1.4

seconds, Stapp was subjected to more Gs than anyone had ever willingly endured. He wasn't just proving that

people could survive a high-speed ejection, he was establishing the parameters of human survivability to G

force: new biological boundaries were being set.

That successful run on 10 December 1954 provided Colonel Stapp with an opportunity he had longed for - to

promote the cause of automobile safety. Stapp had long realised that his research was just as applicable to cars

as it was to airplanes. At every opportunity, Stapp urged the car industry to examine his crash data, and to

design their cars with safety in mind. He lobbied hard for the installation of seat belts and improvements such as

collapsing steering wheels.

'I'm leading a crusade for the prevention of needless deaths,' he told Time magazine in 1955. Stapp's work in

aeronautics and automobiles continued right up until his death in 1999 at age 89. He had received numerous

awards and honours. But the best was the knowledge that his work had helped to save many lives, not just in

aviation, but on highways around the world.