Directions： Decide which of the choices givenbelow would correctly complete the passage ifinserted in the corresponding blanks. Select thecorrect choice for each blank.

Flight simulator (飞行模拟器) refers to anyelectronic or mechanical system for training airplaneand spacecraft pilots and crew member bysimulating flight conditions. The purpose ofsimulation is not to completely substitute (1)_____ actual flight training but to thoroughlyfamiliarize students with the vehicle (2)_____before they (3)_____ extensive and possibly dangerous actual flight training. Simulationsalso is useful for review and for familiarizing pilots with new (4)_____ to existing craft.

Two early flight simulators appeared in England within a decade after the first flight ofOrville and Wilbur Wright. They were designed to enable pilots to stimulate simple aircraft(5)_____ in three dimensions： nose up or down; left wing high and right low， or viceversa; and (6)_____ to left or right. It took until 1929， however， for a truly effectivesimulator， the Link Trainer， to appear， devised by Edwin A. Link， a self-educated aviatorand inventor from Binghamton， New York. (7)_____， airplane instrumentation had beendeveloped sufficiently to permit “blind” flying on instruments alone， but training pilots to do soinvolved (8)_____ risk. Link built a model of an airplane cockpit equipped (9)_____instrument panel and controls that could realistically stimulate all the movements of anairplane. Pilots could use the device for instrument training， manipulating the controls (10)_____ instrument readings so as to maintain straight and level flight or (11)_____ climb ordescent with no visual reference (12)_____ any horizon except for the artificial one on theinstrument panel. The trainer was modified (13)_____ aircraft technology advanced.Commercial airlines began to use the Link Trainer for pilot training， and the US governmentbegan purchasing them in 1934， (14)_____ thousands more as World War II approached.

Technological advances during the war， particularly in electronics， helped to make theflight simulator increasingly (15)_____. The use of efficient analog computers in the early1950s led to further improvements. Airplane cockpits， controls， and instrument displays hadby then become so individualized that it was no longer feasible to use a generalized trainer toprepare pilots to fly anything (16)_____ the simplest light planes. By the 1950s， the US AirForce was using simulators that precisely (17)_____ the cockpits of its planes. During theearly 1960s (18)_____ digital and hybrid computers were adopted， and their speed andflexibility revolutionized simulation systems. Further advances in computer and (19)_____technology， notably the development of virtual-reality simulation， have made it possible to(20)_____ highly complex real-life conditions.

1. A. for 　B. to　C. withD. on

2.　A. concerning B. concern 　C. being concerned 　D. concerned

3. 　A. undertake 　B. undergo 　C. underplay 　D. underuse

4. 　A. models B. modifications　C. modifiers　D. modica

5.　A. manifestations　B. manipulationsC. manifestoes　D. maneuvers

6.　A. yawlingB. yawning　C. yawingD. yawping

7.　A. From then on　B. From now onC. By now　D. By then

8.　A. considerableB. considerate　C. consideringD. considered

9.　A. forB. in　C. withD. on

10.　A. on the part of　B. on the basis of　C. on the track ofD. on the verge of

11.　A. controlB. controllable　C. controlled　D. controller

12.　A. toB. forC. on　D. in

13.　A. as forB. as to　C. as　D. for

14.　A. acquiringB. requiring　C. sustaining　D. retaining

15.　A. actualB. realisticC. realizingD. true

16.　A. exceptB. except forC. apart from　D. but

17.　A. replenishedB. replaced　C. replicatedD. reposed

18.　A. electronicB. electricC. electricityD. electron

19.　A. programB. programmableC. programmedD. programming

20.　A. resurrectB. reproduceC. resuscitate 　D. resume

答案：

1.A 2. D 3. B 4. B 5. D 6. C

7. D 8. A 9. C 10. B 11. C 12. A

13. C 14. A 15. B 16. D 17. C 18. A

19. D 20. B