[西安交通大学2019秋]专业英语（高起专）在线作业（全部答案）

1、【奥鹏】西交专业英语在线作业（全部答案）试卷总分:100    得分:100第1题,Resistors are (  ) elements.A、passiveB、activeC、independent sourcesD、dependent sources正确答案:A第2题,An electric heater draws 10 A from a 120V line. The resistance of the heater is (  ).A、1200B、120C、12D、1.2正确答案:C第3题,The algebraic sum of all voltages around a loop is (  ).A、zeroB、indefinite valueC、sum of voltage risesD、sum of voltage drops正确答案:A第4题,ON-OFF information can be represented by (  ) signal.A、a digitalB、an analogC、a discr

2、eteD、a control正确答案:A第5题,The process quantizing the continuous values into a binary scale is called (  ).A、digital-to-analog conversionB、digital-to-digital conversionC、analog-to-digital conversionD、analog-to-analog conversion正确答案:C第6题,The wide application of operational amplifiers lies in advantage of using (  ).A、positive feedback networksB、large open-circuit gainC、negative feedback networksD、small output impedance正确答案:C第7题,When an induction motor with 10 poles is supplied by 50Hz thre

3、e-phase ac power source, the synchronous revolutions per minute is (  ).  (Synchronous r/min = 120 f/p)A、1000B、900C、700D、600正确答案:D第8题,The electric machine that operates at speeds above synchronous speed works in (  ) region.A、motoringB、generatingC、pluggingD、stopping正确答案:B第9题,A transformer is a device that can convert one ac voltage to another ac voltage through the action of (  ).A、an electric circuitB、a magnetic fieldC、an electric fieldD、a coupling circuit正确答案:B第10题,The prim

4、ary winding is connected to (  ).A、the power sourceB、the loadC、the measurement instrumentD、the motor正确答案:A第11题,Copper losses are (  ) losses in the primary and secondary windings of the transformer core.A、inductiveB、capacitiveC、resistiveD、reactive正确答案:C第12题,(  ) can provide an asynchronous link between two ac electric power system with different nominal frequencies.A、The HVDC (high voltage DC) transmissionB、The EHV (extra-high voltage) AC transmissionC、The AC distributionD、Generat

5、ors正确答案:A第13题,The generator voltages are usually stepped up to the transmission voltage level by (  ).A、series capacitorB、parallel reactorsC、step-up transformersD、step-down transformers正确答案:C第14题,The objective of the optimal economic operation of power systems is (  ).A、to minimize the total production costB、to maintain frequency constantC、to maintain voltages constantD、to ensure balance between generation and load正确答案:A第15题,Any protection scheme consists basically of (  ).A、two e

6、lementsB、three elementsC、four elementsD、five elements正确答案:A第16题,The protective scheme that senses zero sequence current and operates as necessary is called as (  ).A、overcurrent protectionB、zero sequence protectionC、negative sequence protectionD、directional protection正确答案:B第17题,The distance protection is applied to protect (  ).A、transformersB、generatorsC、transmission linesD、buses正确答案:C第18题,The thermal energy of the steam is converted into (  ) energy by the turbine.A、electricalB、

7、mechanicalC、chemicalD、potential正确答案:B第19题,(  ) is used as coolant in light-water reactors.A、GasB、Organic compoundC、Molten saltD、Water正确答案:D第20题,In the form of (  ) the output is continuously fed back and compared with the reference input.A、continuous controlB、discontinuous controlC、discrete-data controlD、sampled-data control正确答案:A第21题,The overall transfer function is the ratio of the transform of the controlled variable to the transform of (  ).A、the controlled variableB、the refer

8、ence inputC、the feedbackD、the output variable正确答案:B第22题,The systems characteristic equation can be used to determine (  ) of a linear time-invariant system.A、the stabilityB、magnitude of the steady-state errorC、the controllabilityD、the observability正确答案:A第23题,In the root-locus method the actual time response of a system can be obtained by means of (  ).A、the inverse Fourier transformB、the inverse Laplace transformC、the Fourier transformD、the Laplace transform正确答案:B第24题,The Buck(降压式变换器)

9、is a (  ) converter.A、voltage step-upB、current step-downC、current step-upD、resistance正确答案:C第25题,Most desktop computers use a separate (  ) as a display device, where notebook computers use a flat panel LCD screen (liquid crystal display screen) that attached to the system unit.A、keyboardB、MouseC、MonitorD、hard disk正确答案:C第26题,A desktop computers sound card sends signals to external (  ).A、printerB、speakerC、ModemD、keyboard正确答案:B第27题,Data stored in RAM (  ) when the power of the computer is turned off.A、is held permanentlyB、permanently disappearsC、is held temporarilyD、temporarily disappears正确答案:B第28题,The notebook computers use (  ) as standard display equipment.A、CRT displayB、L

《[西安交通大学2019秋]专业英语（高起专）在线作业（全部答案）》由会员52082****.com分享，可在线阅读，更多相关《[西安交通大学2019秋]专业英语（高起专）在线作业（全部答案）》请在金锄头文库上搜索。