【判断题】城市轨道交通的信号系统是城市轨道交通系统中最重要的设备之一。其作用是指挥行车,保证安全、高效的列车运行。
【简答题】用电流表和电压表测量干电池的电动势和内阻时 , 所采用的电路如图甲所示。不断改变电阻 R 的大小 , 测出多组电压 U 和电流 I 的值 , 作出 U-I 图线如图乙所示 , 由图乙中的图线可得出电源的电动势 E= V , 内阻 r= Ω , 如果考虑电表的电阻对测量的影响 , 与真实值相比 , 测量值 E 要比真实值 ( 填 “ 偏大 ”“ 偏小 ” 或 “ 相等 ” ) 。
【单选题】用一直流电压表和一直流电流表测量一分流器的电阻时,常用两种接线方式:甲分流器与电流表串联后再与电压表并联;乙分流器与电压表并联后再与电流表串联,比较两种接线的测量误差,()。(这就是高中物理里电路中电流表的内接和外接)
【单选题】您在做维修工作时会用到测电笔。请问须多久检查一次测电笔的功能性。
【单选题】____是城市轨道交通信号系统的重要组成部分,它是保证行车安全,防止列车进入前方列车占用区段和防止列车超速运行的信号设备。
【单选题】听力原文:W: I'm tired of driving all the way to work and back every day. If only cars could drive themselves! M: Well, some car manufactures are working on them. I guess you'll soon buy one if you can aff...
A.
Driving to work is really a headache.
B.
The woman will be able to buy an intelligent car.
C.
Cars that drive themselves may be very expensive.
D.
He is working with a car producer on intelligent cars.
【简答题】完形填空。 I was driving home from a meeting this evening about 5, stuck in traffic on Colorado Blvd, and my car started to choke and then died. I barely managed to walk into a gas station, 1 only that I w...
【单选题】Look at the trouble I am in! If only I ________ more careful when driving. [ ]
【单选题】城市轨道交通通信系统是保证列车( )的设备。