1、       Flight simulator（飞行模拟器）refers to any electronic system for training airplanes, spacecraft pilots and crew members by simulating flight conditions. The purpose of simulation is not to completely take the place of   36   flight training but to thoroughly make the members familiar with the airplane   37   they suffer   38   danger in actual flight training. Simulation is also useful for familiarizing pilots with new adjustment to    39   planes.

       Two early flight simulators appeared in England within a decade after the first flight of Orville and Wilbur Wright. They were    40   to enable pilots to stimulate simple aircraft control in three aspects: nose up or down; left wing high and right low, or vice versa（反之亦然）. Until 1929, however, a truly    41   simulator, the Link Trainer, appeared, designed by Edwin A. Link.   42   , airplane instrumentation had been developed to   43   “blind”flying on instruments alone,   44   training pilots to do so was risky. Pilots could use the equipment for instrument training and the controls   45   instrument guidance so as to keep straight and level flight or control climb or   46   without visual reference   47   any horizon except for the man-made one on the instrument panel（仪表板）. The trainer was improved   48   aircraft technology advanced.

       Technological advances during the war, particularly in   49  , helped to make the flight simulator realistic. The use of efficient computers in the early 1950s led to further   50  . It was no longer possible to use a trainer who couldn’t adapt to special environment to prepare pilots to fly anything but the   51   light planes. During the early 1960s electronic digital computers were   52  , and their speed and flexibility（机动性）   53   a great change in simulation systems. Further advances in computer   54   technology, especially the development of simulation, have made it possible to reproduce highly complex   55   conditions.