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【单选题】
With the development of the society, especially the development of economy, the life both in countryside and city changes a lot. Who are still dwelling on the old life? In the villages of the English countryside there are still people who remember the good old days when no one bothered to lock their doors. There simply wasn't any crime to worry about. Amazingly, these happy times appear still to be with us in the world's biggest community. A new study by Dan Farmer, a gifted programmer, using an automated investigative program of his own called SATAN, shows that the owners of well over half of all World Wide Web sites have set up home Without fitting locks to their doors. SATAN can try out a variety of well-known hacking tricks on an Internet site without actually breaking in. Farmer has made the program publicly available, amid much criticism. A person with evil intent could use it to hunt down sites that are easy to burgle. But Farmer is very concerned about the need to alert the public to poor security and, so far, events have proved him right. SATAN has done more to alert people to the risks than cause new disorder. So is the Net becoming more secure? Far from it. In the early days, when you visited a Web site your browser simply looked at the content. Now the Web is full of tiny programs that automatically download when you look at a Web page, and run on your own machine. These programs could, if their authors wished, do, all kinds of nasty things to your computer. At the same time, the Net is increasingly populated with spiders, worms, agents and other types of automated beasts designed to penetrate the sites and seek out and classify information. All these make wonderful tools for antisocial ,people who want to invade weak sites and cause damage. But let's look on the side. Given the lack of locks, the Internet is surely the world's big gest(almost) crime-free society. Maybe that is because hackers are fundamentally honest. Or that there currently isn't much to steal. Or because vandalism isn't much fun unless you have a peculiar dislike for someone. Whatever the reason, let's enjoy it while we can. But expect it all to change, and security to become the number one issue, when the most influential inhabitants of the Net are selling services they want to be paid for. By saying'...owners of well over half of all World Wide Web sites have set up home with out fitting locks to their doors' (Line 3-4, Para.2), the author means that______.
A.
those happy times appear still to be with us
B.
there simply wasn't any crime to worry about
C.
many sites are not well-protected
D.
hackers try out tricks on an Internet site without actually breaking in
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【判断题】当场效应管的漏极直流电流ID从2mA变为4mA时,它的低频跨导增大()
A.
正确
B.
错误
【多选题】在面试过程中,存在许多非言语信息。搔头这一动作传达的非言语信息是()。
A.
紧张、害怕
B.
迷惑不解
C.
不相信
D.
厌倦
【简答题】区别F - 、F + 、Hfr、F'几个不同的概念。
【多选题】配套系的优越性表现在
A.
配套系种畜禽的推广能有力地推动产业化经营
B.
配套系种畜禽的推广提高生产水平
C.
配套系商品畜禽的商品价值高
D.
配套系商品畜禽能带来显著的经济效益
【判断题】某产品质量标准要求焊缝质量为 II 级合格,现某焊缝 RT 射线检测结果表明,焊缝存在气孔和夹渣,按缺陷评定标准,其焊缝质量评为 I 级。所以该焊缝的气孔和夹渣不需要返修处理,可次不管。
A.
正确
B.
错误
【简答题】以袁隆平为代表的我国杂交水稻研发团队长期不懈奋斗,持续创造,不断挖掘水稻高产的潜力,取得了举世瞩目的成就。为 “ 确保国家粮食安全,把中国人的饭碗牢牢端在自己手中 ” 和世界粮食生产发展作出了卓越贡献。 几十年来,研发团队奔走在试验田和实验室,解决了杂交水稻育种的一系列关键性难题。 1973 年,实现了不育系、保持系和恢复系的 “ 三系 ” 配套育种; 1989 年,两系法杂交水稻育种获得成功; ...
【多选题】头足纲生物运动灵活,擅长伏击和捕食,头足类相比于其他软体动物其优越性表现在哪些方面
A.
足部特化为腕和漏斗,腕足与其上的吸盘大大提高了头足类的捕食效率,漏斗可以控制射水方向,使头足类的运动更为灵活
B.
外套膜多呈流线型具发达肌肉,不但减少水的阻力还可以保护内部组织,头足类贝壳大多退化,运动能力强
C.
具闭管式的循环系统,血液一直在血管中流动,由此可以更有效地到达需氧的器官
D.
头部明显,有发达的神经系统和视觉能力,有些种类喙中具有颚片配合齿舌,大大提高进食效率
【多选题】通常将信道中传输模拟信号的通信系统称为 [填空(1)] ,将信道中传输数字信号的通信系统称为 [填空(2)] 。
A.
模拟通信系统
B.
数字通信系统
【多选题】下列关于管网的敷设方式说法正确的有( )。
A.
供热管道的敷设方式可分为地下敷设和地上敷设两种
B.
直埋敷设是将管道直接埋在地下的土壤内
C.
地上散设不受地下水位的影响
D.
将管道敷设在地沟内称为地沟敷设
E.
地上敷设又称为架空敷设
【单选题】当场效应管的漏极电流 从2mA增加到4mA,它的低频跨导 将
A.
增大
B.
减小
C.
不变
D.
无法确定
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