Unit two

　　Text 1

　　For centuries men dreamed of achieving vertical flight. In 400 A.D. Chinese children played with a fan-like toy that spun upwards and fell back to earth as rotation ceased. Leonardo da Vinci conceive the first mechanical apparatus, called a “Helix,” which could carry man straight up, but was only a design and was never tested.

　　The ancient-dream was finally realized in 1940 when a Russian engineer piloted a strange looking craft of steel tubing with a rotating fan on top. It rose awkwardly and vertically into the air from a standing start, hovered a few feet above the ground, went sideways and backwards, and then settled back to earth. The vehicle was called a helicopter.

　　Imaginations were fired. Men dreamed of going to work in their own personal helicopters. People anticipate that vertical flight transports would carry millions of passengers as do the airliners of today. Such fantastic expectations were not fulfilled.

　　The helicopter has now become an extremely useful machine. It excels in military missions, carrying troops, guns and strategic instruments where other aircraft cannot go. Corporations use them as airborne offices, many metropolitan areas use them in police work, construction and logging companies employ them in various advantageous ways, engineers use them for site selection and surveying, and oil companies use them as the best way to make offshore and remote work stations accessible to crews and supplies. Any urgent mission to a hard-to-get-to place is a likely task for a helicopter. Among their other multitude of used: deliver people across town, fly to and from airports, assist in rescue work, and aid in the search for missing or wanted persons.

　　11. People expect that ________.

　　[A] the airliners of today would eventually be replaced by helicopters

　　[B] helicopters would someday be able to transport large number of people from place to place as airliners are now doing

　　[C] the imaginations fired by the Russian engineer’s invention would become a reality in the future(B)

　　[D] their fantastic expectations about helicopters could be fulfilled by airliners of today

　　12. Helicopters work with the aid of ________.

　　[A] a combination of rotating devices in front and on top

　　[B] a rotating device topside

　　[C] one rotating fan in the center of the aircraft and others at each end(B)

　　[D] a rotating fan underneath for lifting

　　13. What is said about the development of the helicopter?

　　[A] Helicopters have only been worked on by man since 1940.

　　[B] Chinese children were the first to achieve flight in helicopters.

　　[C] Helicopters were considered more dangerous than the early airplanes.(D)

　　[D] Some people thought they would become widely used by average individuals.

　　14. How has the use of helicopters developed?

　　[A] They have been widely used for various purposes.

　　[B] They are taking the place of high-flying jets.

　　[C] They are used for rescue work.(A)

　　[D] They are now used exclusively for commercial projects.

　　15. Under what conditions are helicopters found to be absolutely essential?

　　[A] For overseas passenger transportation.

　　[B] For extremely high altitude flights.

　　[C] For high-speed transportation.(D)

　　[D] For urgent mission to places inaccessible to other kinds of craft.