Cloze
Directions: Decide which of the choices given below would correctly complete the passage if inserted in the corresponding blanks.    Select the correct choice for each blank.

Flight simulator (飞行模拟器) refers to any electronic or mechanical system for training airplane and spacecraft pilots and crew member by simulating flight conditions.    The purpose of simulation is not to completely substitute (1)_____ actual flight training but to thoroughly familiarize students with the vehicle (2)_____ before they (3)_____ extensive and possibly dangerous actual flight training.    Simulations also 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 of Orville 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 vice versa; and (6)_____ to left or right.    It took until 1929, however, for a truly effective simulator, the Link Trainer, to appear, devised by Edwin A. Link, a self-educated aviator and inventor from Binghamton, New York.    (7)_____, airplane instrumentation had been developed sufficiently to permit "blind" flying on instruments alone, but training pilots to do so involved (8)_____ risk.    Link built a model of an airplane cockpit equipped (9)_____ instrument panel and controls that could realistically stimulate all the movements of an airplane.    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 or descent with no visual reference (12)_____ any horizon except for the artificial one on the instrument panel.    The trainer was modified (13)_____ aircraft technology advanced.    Commercial airlines began to use the Link Trainer for pilot training, and the US government began purchasing them in 1934, (14)_____ thousands more as World War II approached.
Technological advances during the war, particularly in electronics, helped to make the flight simulator increasingly (15)_____.    The use of efficient analog computers in the early 1950s led to further improvements.    Airplane cockpits, controls, and instrument displays had by then become so individualized that it was no longer feasible to use a generalized trainer to prepare pilots to fly anything (16)_____ the simplest light planes.    By the 1950s, the US Air Force was using simulators that precisely (17)_____ the cockpits of its planes.    During the early 1960s (18)_____ digital and hybrid computers were adopted, and their speed and flexibility 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. with
D. on
正确答案是

2.
A. concerning
B. concern
C. being concerned
D. concerned
正确答案是

3.
A. undertake
B. undergo
C. underplay
D. underuse
正确答案是

4.
A. models
B. modifications
C. modifiers
D. modica
正确答案是

5.
A. manifestations
B. manipulations
C. manifestoes
D. maneuvers
正确答案是

6.
A. yawling
B. yawning
C. yawing
D. yawping
正确答案是

7.
A. From then on
B. From now on
C. By now
D. By then
正确答案是

8.
A. considerable
B. considerate
C. considering
D. considered
正确答案是

9.
A. for
B. in
C. with
D. on
正确答案是

10.
A. on the part of
B. on the basis of
C. on the track of
D. on the verge of
正确答案是

11.
A. control
B. controllable
C. controlled
D. controller
正确答案是

12.
A. to
B. for
C. on
D. in
正确答案是

13.
A. as for
B. as to
C. as
D. for
正确答案是

14.
A. acquiring
B. requiring
C. sustaining
D. retaining
正确答案是

15.
A. actual
B. realistic
C. realizing
D. true
正确答案是

16.
A. except
B. except for
C. apart from
D. but
正确答案是

17.
A. replenished
B. replaced
C. replicated
D. reposed
正确答案是

18.
A. electronic
B. electric
C. electricity
D. electron
正确答案是

19.
A. program
B. programmable
C. programmed
D. programming
正确答案是

20.
A. resurrect
B. reproduce
C. resuscitate
D. resume
正确答案是

答案：