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阅读大概理解文章意思,不必一句一词翻译出来、 The History of Electricity As early as the latter part of 16th century, experimenters were exploring the behavior of static electricity. Willian Gilbert experimented with electric charges and discharges. In 1750, Benjamin Franklin proved that lightning was electrical in nature. Neither investigator, discovered anything that was significant from the standpoint of electricity. Discovery of the presence of magnetism in certain rocks preceded the earliest knowledge of electricity. Such knowledge was common about 600 B. C. Applications of electrical knowledge were completely absent in this era. In 1800 Alessandro Volta discovered the principle of the electric battery. The voltaic cell was one of the most important discoveries in the history of the electrical art, because it provided a continuous source of appreciable amounts of electric power at reasonable low voltage. It was an essential component of the early communication systems, such as the telephone and telegraph. The first United States’ patent on the electrical telegraph was obtained by Jonhn Groat in 1800. The invention of a practical electromagnet was announced by Joseph Henry in 1827. These inventions by Groat and Henry opened the way for a still more significant invention, the electromagnetic telegraph. The principle of this forerunner of the communications industry was conceived in 1830, proven practical in 1837, and patented in 1840 by Samuel Finley Bressse. Morse. Few developments have had greater impact on American life than Morse’s invention. His idea paved the way for the first system of electrical communication, this in turn led to the telephone and later to the wireless telegraph. The discovery of electromagnetic induction by Michael Faraday in 1831 established many principles for modern machines. One of the first important developments based on the disclosures of Faraday was the DC generator. Motors generators, transformers and many other electrical devices found in heavy electrical industry were made possible by the discoveries of Faraday. The contributions of Faraday in the electrical power industry and comparable to those of Morse in the field of communications. With the development of the high-resistance carbon filament lamp by Thomas Edison in 1880, the DC generator became one of the essential components of the constant-potential lighting system. Commercial lighting and residential lighting became practical and the electric light and power industry were born. One of the most common uses for direct current during this period was for street lighting. The first transformer was announced in 1883. This device probably did more to revolutionize that the high-voltage low-current systems over the low-voltage high–current systems of power transmission were well-known. Following the discovery of the transformed to higher voltages for transmission over great distances (several hundred miles), and then reduce by transformers to lower values for utilization. In 1888 Nikola Tesla was granted a patent on the polyphase AC induction motor, which soon became the most commonly used motor for supplying large amounts of power in its improved state. It is most extensively used today . In 1876 Alexader Graham Bell invented the telephone. This device was soon put into use and, as a result, another huge industry was established. New Words static ['stætɪk] adj. 静电的;静止的;静态的 standpoint ['stæn(d)pɒɪnt] n. 立足点 magnetism ['mægnɪtɪz(ə)m] n. 磁场,磁力 voltaic [vɒl'teɪɪk] adj. 付打的 patent ['pæt(ə)nt; 'peɪt(ə)nt] n. 专利 electromagnetic [ɪ,lektrə(ʊ)mæg'netɪk] n. 电磁铁;电磁体 filament ['fɪləm(ə)nt] n. 灯丝 polyphase ['pɒlɪfeɪz] adj. 多相的
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举一反三
【单选题】已知 x = 3,那么执行语句 x + 6 之后,x的值为
A.
3
B.
6
C.
9
【判断题】组织设计的目的是为了最终实现组织的目标。
A.
正确
B.
错误
【简答题】背景资料 某开发商投资兴建办公楼工程,建筑面积9600m 2 ,地下一层,地上八层,现浇钢筋混凝土框架结构,经公开招投标,某施工单位中标,中标清单部分费用分别是:分部分项工程费3793万元,措施项目费547万元。脚手架费用为336万元。暂列金额100万元。其他项目费200万元,规费及税金2万元,双方签订了工程施工承包合同。 施工单位为了保证项目履约,进场施工后立即编制项目管理规划大纲,实施...
【单选题】风扇皮带的松紧度,一般用大拇指以30~50N的力,按下皮带产生( ) 的挠 度为宜。
A.
5~10mm
B.
10~15mm
C.
15~20mm
D.
20~25mm
【判断题】组织结构设计的出发点是为了合理分配职权与责任,充分调动每一位员工的积极性与创造性,最终实现组织的目标。
A.
正确
B.
错误
【判断题】已知x=3,那么执行语句x+=6之后,x的内存地址不变。
A.
正确
B.
错误
【简答题】背景资料 某开发商投资兴建办公楼工程,建筑面积9600m 2 ,地下一层,地上八层,现浇钢筋混凝土框架结构,经公开招投标,某施工单位中标,中标清单部分费用分别是:分部分项工程费3793万元,措施项目费547万元。脚手架费用为336万元。暂列金额100万元。其他项目费200万元,规费及税金2万元,双方签订了工程施工承包合同。 施工单位为了保证项目履约,进场施工后立即编制项目管理规划大纲,实施...
【单选题】6风扇皮带的松紧度,一般用大拇指以30~50N的力,按下皮带产生的挠度为()。
A.
5~10mm
B.
10~15mm
C.
15~20mm
D.
20~25mm
【简答题】背景资料 某开发商投资兴建办公楼工程,建筑面积9600m 2 ,地下一层,地上八层,现浇钢筋混凝土框架结构,经公开招投标,某施工单位中标,中标清单部分费用分别是:分部分项工程费3793万元,措施项目费547万元。脚手架费用为336万元。暂列金额100万元。其他项目费200万元,规费及税金2万元,双方签订了工程施工承包合同。 施工单位为了保证项目履约,进场施工后立即编制项目管理规划大纲,实施...
【简答题】背景资料 某开发商投资兴建办公楼工程,建筑面积9600m 2 ,地下一层,地上八层,现浇钢筋混凝土框架结构,经公开招投标,某施工单位中标,中标清单部分费用分别是:分部分项工程费3793万元,措施项目费547万元。脚手架费用为336万元。暂列金额100万元。其他项目费200万元,规费及税金2万元,双方签订了工程施工承包合同。 施工单位为了保证项目履约,进场施工后立即编制项目管理规划大纲,实施...
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