Lesson one Text A Cloze Complete the following short passages with the words or phrases listed in the table. Early Aviation Pioneers A .duplicate B. document C. intense D. exhibit E. instead of F. suspend G. rigorous H. invent I. unmanned J. promote During the last years of the 18th century, Sir George Cayley started the first ____(1)___ study of the physics of flight. In 1799, he (2) a plan for a glider, which except for planform was completely modern in having a separate tail for control and having the pilot ___(3)____ below the center of gravity ( 重心 ) to provide stability, and flew it as a model in 1804. Over the next five decades, Cayley worked on and off on the problem, during which he 4 most of basic aerodynamic theory, introducing such ideas as lift and drag . He used both internal and external combustion engines, fueled by gunpowder in his models. Later, Cayley turned his research to building a full-scale version of his design, first flying it 5 in 1849, and in 1853 his coachman made a short unpowered gliding flight at Brompton , near Scarborough in Yorkshire. The 1880s became a period of (6) study characterized by the “ gentleman scientists ” who represented most research efforts until the 20th century. Starting in the 1880s advances were made in construction that led to the first truly practical gliders . Three people in particular were active: Otto Lilienthal , Percy Pilcher and Octave Chanute . Otto Lilienthal of Germany (7) Wenham's work and greatly expanded on it in 1874, publishing his research in 1889. He also produced a series of gliders, and starting in 1891 was able to make flights of 25 meters or more routinely. He rigorously (8) his work, including photographs, and for this reason is one of the best known of the early pioneers. He also (9) the idea of “jumping before you fly”, suggesting that researchers should start with gliders and work their way up, (10) simply designing a powered machine on paper and hoping it would work. His type of aircraft is now known as a hang glider 悬挂式滑翔机 .