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【简答题】
For years and years people have been saying that the railways are dead. “We can do without railways.” people say, as if motorcars and planes made the railways unnecessary. We all keep hearing that trains are slow, that they lose money, that they're dying. But this is far from the truth. In these days of expensive oil, the railways have become highly competitive with motorcars and planes. If you want to carry people or goods from place to place, they're cheaper than planes. And they have much in common with planes. A plane goes in a strange line and so does a railway. What is more, it takes you from the heart of a city into the heart of another. It doesn't leave you as a plane does, miles and miles from the city center. It doesn't hold you up as a car does, in endless traffic jams. And a single train can carry goods which no plane or motorcar could ever do. Far from being dead, the railways are very much alive. Modern railway lines give you a smooth, untroubled journey. Where else can you eat well, sleep in comfort, feel safe and enjoy the scene while you are traveling at speed at the same time? And we are only at the beginning. For we have just entered the age of super­fast trains, traveling at 150 miles an hour and more. Soon we will be wondering why we spent so much on motorways we can't use because we have not enough money to buy the oil and planes we can't fly in for the same reason.
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参考答案:
举一反三
【单选题】江西全省有12.57万少数民族,分属于( )个少数民族。
A.
23
B.
32
C.
42
D.
52
【单选题】图示电路参数为VDD=VSS=5V,Rd=5kΩ,Rs=2kΩ,RL=5kΩ。场效应管参数Kn=3mA/V2,λ=0。若IDQ=0.37mA,那么电路的小信号电压增益约为( ),输入电阻约为( )。【图片】
A.
5.25,384Ω
B.
-5.25,2kΩ
C.
-5.25,384Ω
D.
5.25,2kΩ
E.
1.85,2.5kΩ
【单选题】图示电路参数为【图片】【图片】场效应管参数【图片】若【图片】那么电路的小信号电压增益约为_________,输入电阻约为__________。【图片】
A.
5.25 , 384
B.
- 5.25 , 2
C.
- 5.25 , 384
D.
5.25 , 2
E.
1.85 , 2.5
【判断题】煅白矾时应不断搅拌以促进结晶水的蒸发。 ( )
A.
正确
B.
错误
【单选题】1939年1月.国民党江西省党部、省政府由南昌迁到吉安,几个月后迁到泰和.1945年初迁至宁都。根据所学知识分析,国民党江西省党部、省政府这几次辗转迁徙的原因最有可能是()
A.
北伐战争胜利进军
B.
国民党军队围剿红军
C.
侵华日军步步进逼
D.
人民解放军渡江作战
【判断题】供给弹性越大,生产商的税收负担就会越小,而供给弹性越小,生产商的税收负担就会越大。
A.
正确
B.
错误
【判断题】只要在境内储存、加工、装配后复运出境的货物,都可以按保税货物进行监管。
A.
正确
B.
错误
【单选题】图示电路参数为I=0.5mA,VDD=VSS=5V,Rg=100 kΩ,Rd=10kΩ, Rsi=1kΩ。场效应管参数为VTN=1V,Kn=0.5【图片】,λ=0。那么电路的输入电阻约为________,源电压增益Aυs=υo/υs =_________,输出电阻约为________。【图片】
A.
2 k W , 5 , 10k W
B.
0.5k W , -5 , 10k W
C.
1 k W , -5 , 10k W
D.
1 k W , 5 , 10k W
【判断题】ROC曲线越向左上偏,曲线下的面积越大,其识别能力也就是临床准确性越优秀。
A.
正确
B.
错误
【简答题】将图所示电路中的电压源等效变换为电流源的电路参数为______,等效电流源电路图为______。
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