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1、2022年考博英语-西安交通大学考前拔高综合测试题（含答案带详解）1. 写作题For this part, you are required to write a composition of no less than 200 words according to the following topic. Please write your composition clearly on the Answer Sheet provided. (20 points) Many people, especially young people, make friends through QQ chat
2、ting or other forms of instant messaging systems. Some people say that such relationships as QQ networking friends are not trustworthy because tragedies happen occasionally; others say that relationships of such kind are no difference from the traditional ones, because they encounter both good frien
3、d and bad guys through QQ chatting as they do in their traditional life styles; still others believe that whether they are trustworthy or not depends on your initial purpose and how you pursue such a relationship. Whats your opinion about it? Please choose one option and write an essay of at least 2
4、00 words. Please use adequate materials to support your position. 【答案】Should People Make Friends on Line?2. 单选题The helicopter is an incredibly versatile machine. It can fly, straight up or down, hover like a fly, and go forwards, backwards, or sideways. It therefore needs no long, prepared runway li
5、ke a normal airplane does. It can operate from a flat roof in the city or from a clearing in the jungle with equal ease. However, helicopters are nowhere near as fast as normal fixed-wing airplanes and have a top speed of only about 200 miles an hour.The helicopter has often been called the flying w
6、indmill because of the long, rotating blades, or rotor, on top of its body. This main rotor serves as both propeller and wings to provide the thrust to drive the helicopter along and the lift to raise it off the ground. The rotor blades have the same aero-foil shapes as airplane wings and propellers
7、 to generate the required lift and thrust.When the main rotor rotates, the body of the helicopter lends to spin by reaction in the opposite direction. To counteract this effect, a small rotor is mounted sideways on the tail. The thrust produced by this tail rotor in normal flight just balances the t
8、urning tendency of the helicopter body which therefore remains steady. Both the main and the tail rotors are driven by the helicopter engine through the same gearbox. Another way of maintaining stability in the air is to have twin main rotors which each rotate in opposite directions. Then, the spinn
9、ing tendency of one cancels that of the other.Movement of the helicopter in a direction - forwards, backwards, sideways, up or down - is achieved simply by varying the pitch of the rotor blades. The pitch is the angle at which the blades slice through or bite the air. To fly straight upwards all the
10、 blades are set at the same sharp pitch. In this position they achieve maximum lift. To descend, the pitch of the blades is reduced so that the lift is insufficient to support the helicopters weight.The pilot adjusts the pitch for up or down movement by moving the collective-pitch stick. This is als
11、o linked to the engine throttles so that more power is applied as the pitch increases. This is to overcome the greater air resistance with the sharper pitch. Conversely, the engine is throttled back when the pitch is reduced for descent because there is less air resistance.To fly forwards, the pitch
12、 of the rotor blades is varied as they rotate. For forward motion, the pitch is made least at the front and gradually increased as the blade moves backwards. This has the effect of sweeping the air backwards, and therefore pushing the helicopter forwards. The same goes for any horizontal movementthe
13、 pitch is made least in the desired direction of travel. The cyclic-pitch stick controls the pitch of the rotor for horizontal flight.1.From the first paragraph we can infer that（ ） .2.Whats the basic function of the main rotor of a helicopter?3.The movement of the helicopter in any direction is con
14、trolled by（ ） .4.To fly forwards, a helicopter has to （ ） .5.The word descend in line 4 of paragraph 4 can be best replaced by （ ） .6.The phrase This position in line 4 of paragraph 4 refers to （ ） .7.What is the most appropriate title for this passage?问题1选项A.nothing is perfectB.generally speaking,
15、helicopters are better than other airplanesC.fixed-wing airplanes have a top speed of about 200 miles per hourD.helicopters are not at all versatile问题2选项A.To counteract the spinning of a helicopter.B.To maintain stability in the air.C.To rotate in opposite direction.D.To produce the force to drive i
16、t along and the lift to raise it off the ground.问题3选项A.a small rotorB.its tailC.varying the pitch of the rotor bladesD.counteracting maximum lift问题4选项A.support the helicopters weightB.sweep the air backwards and push the helicopter forwardsC.be linked to the engine throttleD.slice through the air问题5选项
