相关试题
【单选题】
25T型客车的逆变器在20 kW负载状态下稳定运行时，突加制冷压缩机负载(功率为4.5～5.5 kW)，逆变器___
A. 必须重新启动
B. 必须停机，3～5 min再启动
C. 应能正常运行
D. 将会跳闸
【单选题】
25T型客车的充电器进行模拟过分相试验：充电器每工作___，输入电源断电10 s，充电器应能正常工作，该项试验连续模拟10次
A. 10 min
B. 1 min
C. 5 min
D. 20 min
【单选题】
25T型客车的充电器在额定输入状态下，突加、突减( )额定负载，充电器应能正常工作 ___
A. 30％
B. 50%
C. 45％
D. 25％
【单选题】
MS730CP6C塞拉门是高速旅客列车使用的系列化外摆塞拉门，控制方式为___
A. 气压控制
B. 电信号控制
C. 计算机控制
D. 液压控制
【单选题】
MS730CP6C塞拉门的车门系统具有___功能
A. 防断电
B. 防挤压
C. 防过压
D. 防漏电
【单选题】
对全车性能试验的车辆应在车体两侧涂打___的白色标记
A. 一条宽为50 mm
B. 一条宽为100 mm
C. 两条宽为50 mm
D. 两条宽为100 mm
【单选题】
爆炸危险品专用车的车体中部四周涂打宽为200 mm的___色带，并在色带中部涂打“危险”字样
【单选题】
车辆滚动轴承使用的润滑脂是___
A. 3号钙基脂
B. 3号钠基脂
C. 3号锂基脂
D. 3号钙钠基脂
【单选题】
___手柄处是不绝缘的
A. 斜口钳
B. 剥线钳
C. 电工刀
D. 断线钳
【单选题】
车轴与车轮的配合属于___
A. 间隙配合
B. 过盈配合
C. 过渡配合
D. 动配合
【单选题】
车辆检修限度中，属于最大限度的是___
A. 厂修限度
B. 段修限度
C. 辅修限度
D. 运用限度
【单选题】
25T型客车的蓄电池组应有短路保护，各极对箱体间的绝缘电阻应不小于___
A. 20 M
B. 10 M
C. 15 M
D. 50 M
【单选题】
对于电路的任一闭合回路，从回路任一点出发，沿回路绕行1周，电位上升之和___电位下降之和
【单选题】
在直流电路中，当负载获得最大功率时，电源的效率为___
A. 30％
B. 50％
C. 80％
D. 100％
【单选题】
在电阻的色环标值识别法中，其中第___表示阻值的误差
A. 一色环
B. 二色环
C. 三色环
D. 四色环
【单选题】
电容器按所用电介质的不同，分为纸介电容器、云母电容器、___、电解电容器等
A. 固定电容器
B. 可变电容器
C. 瓷介电容器
D. 半可变微调电容器
【单选题】
在纯电阻交流电路中，电压与电流的相位关系是___
A. 同相
B. 反相
C. 电压导前电流90°
D. 电压滞后电流90°
【单选题】
硅、锗、硒等物体属于___
A. 导体
B. 半导体
C. 超导体
D. 绝缘体
【单选题】
交流接触器短路环的作用是___
A. 励磁
B. 增加电磁吸力
C. 节电运行
D. 消除振动和噪声
【单选题】
求三相对称负载的有功功率，___是正确的
A. P＝Ｕ相I相cos
B. P＝U相Ｉ相sin
C. P＝Ｕ线Ｉ线sin
D. P＝Ｕ线Ｉ线cos
【单选题】
交流接触器的线圈电压在额定电压的___时，可以可靠地工作
A. 60％～80％
B. 70％～120％
C. 85％～105％
D. 100％～115％
【单选题】
接触器触头采用桥式双断口结构，其目的是利用___原理灭弧
A. 电动力灭弧
B. 磁吹灭弧
C. 窄缝灭弧
D. 栅片灭弧
【单选题】
调整和检查自动空气开关和主接触器的触头应注意触头的___
A. 开距、压力
B. 压力、超程
C. 压力、开距、超程
D. 开距、超程
【单选题】
___不会造成接触器铁芯振动和噪声
A. 短路环损坏或脱落
B. 铁芯端面有锈蚀
C. 线圈电压过低
D. 反作用弹簧力不足
【单选题】
电动机是把___的设备
A. 机械能转换成电能
B. 电能转换成机械能
C. 化学能转换成电能
D. 化学能转换成机械能
【单选题】
异步电动机定子主要由___组成
A. 铁芯、绕组
B. 铁芯、机座
C. 铁芯、绕组、机座
D. 铁芯、绕组、转轴
【单选题】
三角形连接的三相鼠笼式异步电动机，若误接成星形，则输出功率___
A. 下降
B. 不变
C. 增大
D. 视具体情况而定
【单选题】
___不是直流电动机调速的方法
A. 改变电枢回路电阻值
B. 改变励磁电流
C. 改变电枢电压
D. 改变转差率
【单选题】
单相变压器一、二次额定电流是指温升不超过额定值的情况下，一、二次侧绕组所允许通过的最大电流的___
A. 有效值
B. 平均值
C. 幅值
D. 瞬时值
【单选题】
直流电动机如果要实现反转，需要对调电枢电源的极性，其励磁电源极性___
A. 保持不变
B. 同时对调
C. 变与不变均可
D. 视具体情况而定
【单选题】
载流导体在磁场中所受到力的大小与磁通密度，导体的电流大小及___成正比
A. 导体的截面积
B. 导体的长度
C. 导体的有效长度
D. 导体的重量
【单选题】
变压器不能改变___
A. 电压
B. 电流
C. 请输相位
D. 频率
【单选题】
有一感性负载，测得是其电阻为3 ，感抗为4 时则其阻抗为___
【单选题】
有一变压比为2的变压器，如在次级上接50 的电阻，则变压器的输入阻抗为___
A. 200
B. 25
C. 100
D. 12.5
【单选题】
晶体三极管极性的结构有PNP型和___
A. NPN型
B. NNP型
C. PPN型
D. NPP型
【单选题】
用万用表测得二极管正、反向电阻都为无穷大，表明该二极管___
A. 短路
B. 断路
C. 性能不好
D. 正常
【单选题】
将电容器两端线分别与万用表选大电阻挡位时两表笔相连来检查电容，若表针摆动一角度后，慢慢复位，说明该电容___
推荐试题
【单选题】
项目提前终止， 发起人要求提交收尾文件， 以便了解项目的最终情况。 在此份文件中， 项目经理应该注意包括以下信息， 除了 （ ）。
A. 项目终止的原因
B. 项目偏差情况
C. 移交阶段可交付成果的正式程序
D. 项目成员遣散计划
【单选题】
ABB 公司与某水电站业主签订了电站开关站和高压输电线路的设备供货和安装合同。在安装施工过程中， 卖方抱怨买方没有及时为 ABB 公司清理安装现场， 这可能影响工期。 合同规定场地清理是买方的职责之.。 作为买方的项目经理，你将 （ ）。
A. 告诉卖方自己清理安装现场
B. 签发合同变更令， 更改合同
C. 从项目中取消安装现场清理这一工作
D. 预期将收到卖方的合同索赔
【单选题】
需要聘请一位咨询专家为本项目提供技术咨询服务。 现在， 只知道这类咨询服务工作的性质， 还不知道究竟需要多少时日的咨询服务。 为了尽快签订咨询服务合同， 最好采用哪种合同类型？ （ ）
A. 总价合同
B. 成本补偿合同
C. 总价加经济价格调整合同
D. 时间和手段合同
【单选题】
在项目的执行阶段，一个新成员加入了项目团队。项目经理要求他先跟着一个经验丰富的老成员实习一个月。 这种工作跟随方式最有利于 （ ）。
A. 新成员与老成员发展个人友谊
B. 新成员迅速有效地融人团队
C. 新成员学习老成员的显性知识
D. 新成员学习老成员的隐性知识
【简答题】
攻势已经持续了三天，但是我们并没有取得多少进展。师长命令我们营夜晚绕到敌人后方发起突然袭击。然而，要绕到敌人后方，我们必须越过一片沼泽地。我们很多人担心会陷入泥潭之中。我们营长决定冒下险。所幸由于寒冷天气沼泽地都结上了冰，我们于天亮前到达目的地并从敌人后方发起进攻。这一下扭转了战局。敌人没有戒备，不久便投降了。
【简答题】
汽年自从发明以来使交通运输发生了草命性的变化，永远地改变了人们的生活、旅行和办事的方式。但另ー方面，也带来了危害，尤其是公路死亡事故。然而，现今由于计算机技术和电子传感器的使用，有可能消除发生的大多数交通事故。例如，装在你汽车上的电子传感器能检测到空气中的酒精雾汽并拒绝启动引擎。同样，传感器还能通过接受在轨道上运行的卫星发出的信号监测路况并大大减少你陷入交通拥堵的可能性。
【简答题】
常言道，好的开端是成功的一半。在求职时，求职者事先做好充分的准备是非常重要的。我认为，事先做不做准备显然会影响求职者的成功机会。
我的一位朋友在一家大型计算机软件公司供职，年薪十万美元左右。他根据自己的经历告诉我说，那些面试未来雇员的具有录用决定权的人喜欢有充分准备的人。那些没有在了解未来雇主方面尽全力的人很难有成功的希望。
【简答题】
全球化对中国年轻人具有重大影响。例如，年轻的农民正在大规模流向城市寻找工作。而对那些想出国深造或进外企工作的年轻人来说，英语变得越来越重要。另一方面，许多海外学子近年来回归祖国，因为他们看好中国经济的长期增长前景。因特网加强了中国年轻人和其他地方年轻人的联系。他们跟踪最新的潮流，模仿外国的时尚。他们中一些人似乎不在乎中国的传统美德，更不要说发扬光大，这使得有人忧虑中国传统文化会不会有一天终将消失。
【简答题】
就我来说，我发现外表往往是靠不住的。譬如，要是你仅凭外表去判断诸如爱德华・海德・伯顿这样的人，你就错了。外表上，伯顿像是个表里一致的人。他个子很小，满头白发，有着一双温和、蔚蓝的眼睛，文雅且坦率。然而，他原来却是十分的残忍。他侮辱和愚弄穷困潦倒的伦尼，让他去做那样的蠢事。更让人吃惊的是，他对伦尼的死全然冷漠无情。毫无疑问，他是个铁石心肠的家伙。
【简答题】
They say that pride comes before a fall. In the case of both Napoleon and Hitler, the many victories they enjoyed led them to believe that anything was possible, that nothing could stand in their way. Russia's icy defender was to prove them wrong.
【简答题】
In 1812, Napoleon Bonaparte, Emperor of the French, led his Grand Army into Russia. He was prepared for the fierce resistance of the Russian people defending their homeland. He was prepared for the long march across Russian soil to Moscow, the capital city. But he was not prepared for the devastating enemy that met him in Moscow -- the raw, bitter, bleak Russian winter.
【简答题】
In 1941, Adolf Hitler, leader of Nazi Germany, launched an attack against the Soviet Union, as Russia then was called. Hitler's military might was unequaled. His war machine had mowed down resistance in most of Europe. Hitler expected a short campaign but, like Napoleon before him, was taught a painful lesson. The Russian winter again came to the aid of the Soviet soldiers.
【简答题】
In the spring of 1812, Napoleon assembled an army of six hundred thousand men on the borders of Russia. The soldiers were well trained, efficient, and well equipped. This military force was called the Grand Army. Napoleon, confident of a quick victory, predicted the conquest of Russia in five weeks.
【简答题】
Shortly afterwards, Napoleon's army crossed the Neman River into Russia. The quick, decisive victory that Napoleon expected never happened. To his surprise, the Russians refused to stand and fight. Instead, they retreated eastward, burning their crops and homes as they went. The Grand Army followed, but its advance march soon became bogged down by slow-moving supply lines.
【简答题】
In August, the French and Russian armies engaged at Smolensk, in a battle that left over ten thousand dead on each side. Yet, the Russians were again able to retreat farther into Russian territory. Napoleon had won no decisive victory. He was now faced with a crucial decision. Should he continue to pursue the Russian army? Or should he keep his army in Smolensk for the approaching winter?
【简答题】
Napoleon took the gamble of pressing on to Moscow, 448 kilometers away. On September 7, 1812, the French and Russian armies met in fierce battle at Borodino, 112 kilometers west of Moscow. By nightfall, thirty thousand French and forty-four thousand Russians lay dead or wounded on the battlefield.
【简答题】
Again, the Russian army retreated to safety. Napoleon had a clear path to Moscow, but the occupation of the city became an empty victory. The Russians fled their capital. Soon after the French arrived, a raging fire destroyed two-thirds of the city. Napoleon offered a truce to Alexander I, but the Russian czar knew he could bide his time: "We shall let the Russian winter fight the war for us."
【简答题】
Napoleon soon realized he could not feed, clothe, and quarter his army in Moscow during the winter. In October 1812, he ordered his Grand Army to retreat from Moscow.
【简答题】
The French retreat turned into a nightmare. From fields and forests, the Russians launched hit-and-run attacks on the French. A short distance from Moscow, the temperature had already dropped to minus 4 degrees Celsius. On November 3, the winter's first snow came. Exhausted horses fell dead in their tracks. Cannon became stuck in the snow. Equipment had to be burned for fuel. Soldiers took ill and froze to death. The French soldiers dragged on, leaving the dead along every mile.
【简答题】
As the Russian army was gathering its strength, the French had to flee Russia to avoid certain defeat. At the Berezina River, the Russians nearly trapped the retreating French by burning the bridges over the swollen river. But Napoleon, by a stroke of luck, was able to build two new bridges. Thousands of French soldiers escaped, but at the cost of fifty thousand dead. Once across the Berezina, the tattered survivors limped toward Vilna.
【简答题】
Of the six hundred thousand soldiers Napoleon had led into Russia, less than one hundred thousand came back. The weakened French army continued its retreat westward across Europe. Soon, Britain, Austria, Russia, and Prussia formed a powerful alliance and attacked these stragglers. In March 1814, Paris was captured. Napoleon abdicated and went into exile, his empire at an end.
【简答题】
By early 1941, Adolf Hitler, leader of Nazi Germany, had seized control of most of Europe. To the east of Hitler's German empire was the Soviet Union. On June 22, 1941, without a declaration of war, Hitler began an invasion of the Soviet Union that was the largest military land campaign in history. Confident of a quick victory, Hitler expected the campaign to last no longer than three months. He planned to use the blitzkrieg, or "lightning war," tactics that had defeated the rest of Europe. The invasion had three broad thrusts: against Leningrad and Moscow and through the Ukraine.
【简答题】
Caught off guard by the invasion, Soviet leader Joseph Stalin instructed the Russian people to "scorch the earth" in front of the German invaders. Farms and factories were burned, destroyed, or rendered useless. During the first ten weeks of the invasion, the Germans pushed the front eastward, and the Russians suffered more than a million casualties.
【简答题】
In the north, the Germans closed in on Leningrad. Despite great suffering, however, the people of Leningrad refused to surrender. As the battle of Leningrad dragged on into winter, the city's situation became desperate. As food ran out, people died from hunger and disease. By the middle of the winter of 1941-1942, nearly four thousand people starved to death every day. Close to one million people died as a result of the siege.
【简答题】
In the center of Russia, Hitler's goal was the capture of Moscow. Because the Germans had anticipated a quick victory, they had made no plans for winter supplies. October arrived with heavy rains. "General Mud" slowed down the movement of the Germans' lightning attack.
【简答题】
As Hitler's armies drew closer and closer to Moscow, an early, severe winter settled over the Soviet Union, the harshest in years. Temperatures dropped to minus 48 degrees Celsius. Heavy snows fell. The German soldiers, completely unprepared for the Russian winter, froze in their light summer uniforms. The German tanks lay buried in the heavy snowbanks. The Russian winter brought the German offensive to a halt.
【简答题】
By the summer of 1942, Hitler had launched two new offensives. In the south, the Germans captured Sevastopol. Hitler then pushed east to Stalingrad, a great industrial city that stretched for 48 kilometers along the Volga River. Despite great suffering, Soviet defenders refused to give up Stalingrad.
【简答题】
In November 1942, the Russians launched a counterattack. With little or no shelter from the winter cold in and around Stalingrad, German troops were further weakened by a lack of food and supplies. Not until January 1943 did the Germans give up their siege. Of the three hundred thousand Germans attacking Stalingrad, only ninety thousand starving soldiers were left. The loss of the battle for Stalingrad finally turned the tide against Hitler. The German victories were over, thanks in part to the Russian winter.
【简答题】
During 1943 and 1944, the Soviet armies pushed the German front back toward the west. In the north, the Red Army broke the three-year siege of Leningrad with a surprise attack on January 15, 1944. Within two weeks, the heroic survivors of Leningrad saw their invaders depart. By March 1944, the Ukraine farming region was again in Soviet hands. On May 9, 1944, Sevastopol was liberated from the Germans. The Russians were now heading for Berlin.
【简答题】
For Hitler, the invasion of the Soviet Union had turned into a military disaster. For the Russian people, it brought unspeakable suffering. The total Soviet dead in World War II reached almost 23 million.
【简答题】
The elements of nature must be reckoned with in any military campaign. Napoleon and Hitler both underestimated the severity of the Russian winter. Snow, ice, and freezing temperatures took their toll on both invading armies. For the Russian people, the winter was an icy defender.
【单选题】
________不属于鼠类及体表寄生虫携带的病原体。___
A. 鼠疫耶尔森菌
B. 汉坦病毒
C. 黄病毒属病毒
D. 致病性钩端螺旋体
【单选题】
病媒生物死体样本运送，如果在24h内不能到达实验室的，运送过程中箱内温度应保持在_____。___
A. 4℃以下
B. 0℃以下
C. -20℃以下
D. 4℃以上
【单选题】
病媒生物死体样本运送，如果在装箱后4h内能够到达实验室的，运送过程中箱内温度应保持在______。___
A. 4℃以下
B. 0℃以下
C. -20℃以下
D. 4℃以上
【单选题】
病媒生物的死体样本运送，如果4h-24h内能到达实验室的，应将样品置于-30℃冷冻后再送样，运送过程中箱内温度应保持在________。___
A. 4℃以下
B. 0℃以下
C. -20℃以下
D. 4℃以上
【单选题】
恰加斯病也称为美洲锥虫病，其重要的传播媒介是________。___
A. 采采蝇
B. 厩螫蝇
C. 锥蝽
D. 埃及伊蚊
【单选题】
_______是黑热病内脏利什曼病的主要传播媒介。___
【单选题】
对于用作虫媒病毒分离或检测的蚊类标本，现场采集后应采用_______方式处置和运送。___
A. 杀虫剂熏杀+常温运输
B. 等蚊虫自然死亡+常温运输
C. 冷冻处死+常温运输
D. 冷冻处死+冷冻状态运输
【单选题】
_______不适用于入出境集装箱携带蝇、蚊、蠓的采集。___
A. 挥网法
B. 电动吸蚊器法
C. 直接捡取法
D. 二氧化碳诱蚊灯法
【单选题】
入境航空器应在______开始病媒生物监测。___
A. 卸货完成后
B. 抵达后
C. 等航空公司通知
D. 发现病媒生物时
