归纳移动通信的主要特点。-查字典考试网

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个性化吸窗天线水平间距要求保证在6λ～10λ，即()m。

A、0～06
B、1～16
C、2～26
D、3～36

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移动通信系统一般由()构成。

A、发信机
B、收信机
C、天线
D、馈线

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移动通信使用的甚长波的波长范围是()。

A、100～10Mm(108～107m)
B、10～1Mm(107～106m)
C、1000～1000kMm(106～105m)
D、100～10kMm(105～104m)

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移动通信系统中的收信机的主要作用是把天线接收下来的射频载波信号首先进行低噪声放大，然后经过变频、中频放大和解调后还原出原始信号，最后经中频放大器放大输出。

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无线收发信系统中接收机中的()的主要作用是对搬移到中频的信号进行放大。

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Passage 4 Questions 16 to 20 are based on the following passage: The new global satellite communications systems will offer three kinds service, which may overlap in many different kinds of receivers. VOICE. Satellite telephones will be able to make calls from anywhere on the Earth to anywhere else. That could make them especially useful to remote, third world villages (some of which already use stationary satellite telephones), explorers and disaster-relief teams. Today’s mobile telephones depend on earth-bound transmitters, where technical standards vary from country to country. So business travelers cannot use their mobile phones on international trips. Satellite telephones would make that possible. MESSAGING. Satellite massagers have the same global coverage as satellite telephones, but carry text alone, which could be useful for those with laptop computers. Equipped with a small screen like today’s papers, satellite massagers will also receive short messages. TRACKING. Voice and messaging systems will also tell their users where they are to within a few hundred meters. Combined with the messaging service, the location service could help rescue teams to find stranded adventurers, the police to find stolen cars, exporters to follow the progress of cargoes, and haulage companies to check that drivers are not detouring the pub. America’s military Global Positioning System (GPS) satellite will provide better positioning information to anyone who has a receiver for their signals, but GPS does not carry messages, so such a receiver cannot be used on its own for tracking or rescue. By the mid-1990s, GPS receivers will be able to tell people where they are to within 70 meters anywhere in the world, and to within a meter or so in areas where the service is supplemented by ground-based transmitter. 16. Global satellite communications systems will be useful to . A. laptop computer users B. remote villages C. disaster-relief teams D. all above 17. Satellite telephone will make . A. business travelers use mobile phones on international trips B. possible calls from anywhere on earth to anywhere else C. explorers happy D. all above 18. Which of the following is true? A. The positioning precision of the voice system is better than that of GPS. B. The positioning precision of GPS is Better than that of the voice system. C. The positioning precision of the messaging system is better than of GPS. D. The positioning precision of voice system is better than that of the messaging system. 19. What can we say about the new global satellite communications systems? A. They are widely used. B. They are very helpful. C. They are costly. D. Both A and B. 20. Which of the following may be the best title for the passage? A. Global Satellite Communications B. New Voice and Messaging System C. New Generation Satellite D. Always in Touch
Part V Writing Directions: In this part you are required to write an essay about Saving Energies and Resources. You should write at least 120 words and base your composition on the outline (given in Chinese) below: 1、随着社会的发展，厉行节约越来越重要; 2、生活中许多方面都可以节约; 3、每个人都应该养成节约的好习惯。
在基坑开挖中造成坍塌事故的主要原因是什么?
Part III Cloze Directions: There are twenty blanks in the following passage. For each blank there are four choices. Choose the one that best fits into the passage and then marks your answer on the Answer Sheet. What makes a child speak a language has long been a puzzle to linguists. 61 speaking, there are two schools of linguists, both of whom try to explain 62 a child picks up a language so easily. The fact that a child picks a language 63 is 64 : At one year old, a child is able to say “bye-bye”; at two, he is able to use fifty; by there he begins to 65 tenses. The famous American linguist Noam Chomsky 66 that human being have a sort of built-in system for language use, and that the 67 is 68 . Children are not taught language 69 they are taught arithmetic. Other linguists, 70 , hold the view that a child learns 71 of his language from the hints in the environment. 72 , theorists of both schools 73 that there is a biological basis for language use. The 74 is which is more important, the inner ability or the environment. This is certainly a field 75 to be explored. Researchers from both schools are busy finding evidence to 76 their own theory, but 77 side is persuading the other. It seems that in order to 78 why a child learns a language so easily, we have to 79 the joint efforts of both schools. Some linguist, like De Villiers, has recognized the value of cooperation, and 80 linguists of both sides to work together. 61. A. Surprisingly B. Personally C. Properly D. Roughly 62. A. that B. when C. why D. how 63. A. independently B. naturally C. without help D. with ease 64. A. confusing B. surprising C. questioned D. suspected 65. A. master B. study C. have D. get 66. A. doubts B. believes C. realizes D. criticizes 67. A. help B. teacher C. environment D. hint 68. A. quite essential B. very important C. not necessary D. only secondary 69. A. as B. for C. when D. though 70. A. in particular B. as a result C. however D. therefore 71. A. a little B. some C. nothing D. most 72. A. Before B. From now on C. Just now D. By now 73. A. suspect B. disagree C. agree D. realize 74. A. case B. argument C. problem D. question 75. A. waiting B. planning C. never D. unlikely 76. A. provide B. create C. supply D. support 77. A. not a B. one C. neither D. either 78. A. find out B. rule out C. search for D. look for 79. A. get rid of B. trust in C. rely on D. persist in 80. A. ordered B. criticized C. challenged D. urged
某建筑工程，占地面积8000m2, 地下三层，地上三十层，框筒结构，结构钢筋采闲HRB400 等级，底板泯凝土强度等级C35, 地上三层及以下核心筒和柱泯凝土强度等级为C60, 局部区域为两层通高报告厅，其主梁配置了无粘结预应力筋，某施工企业中标后进场组织施工，施工现场场地狭小，项目部将所有材料加工全部委托给专业加工厂进行场外加工。在施工过程中，发生了下列事件：事件一：在项目部依据《建设工程项目管理规范》GB/T50326-200S编制的项目管理实施规划中，对材料管理等各种资源管理进行了策划，在资源管理计划中建立了相应的资源控制程序。事件二：施工现场总平?布置设计中包含如下主要内容： ①材料加工场地布置在场外; ②现场设置一个出入口，出入口处设置办公用房; ③场地周边设置 38m 宽环形载重单车道主干道(兼消防车道 )，并进行硬化，转弯半径 10m; ④在干道外侧开挖400x600mm管沟，将临时供电线缆，临时用水管线埋置于管沟内，监理工程师认为总平面布置设计存在多处不妥，责令整改后再验收，并要求补充主干道具睞硬化方式和裸露场地文明施工防护措施。事件三：项目经理安排土建技术人员编制了《现场施工用电组织设计》，经相关部门审梭，项目技术负责人批准、总监理工程师签认，并组织施工等单位的相关部门和人员共同验收后投入使闲。事件四：本工程推广应用《建筑业10 项新技术 (2010) 》，针对“钢筋及预应力技术”大项，可以在本工程中应用的新技术均制订了详细的推广措施。事件五：设备安装阶段，发现拟安裝在屋面的某空调机组重重超出塔吊限载值(额定起重重 )约 6% 因特殊愔况必须使用该塔吊进行吊裝。经项目技术负责人安全验筲后批准用塔吊起吊;起吊前先进行试吊，即将空调机组吊离地面30cm 后停止提升，现场安排专人进行观察与监护。监理工程师认为施工单位做法不符合安全规定，要求整改，对试吊时的各项检查内容旁站管理。问题 1.事件一中，除材料管理外，项目资源管理工作还包括哪些内容?除资源控制程序外，资源管理计划还应包括哪些内容 ? 2.针对事件二中施工总平?布置设计的不妥之处，分别写出正确做法，施工现场主干道常用硬化方式有哪些 ?裸露场地的文明施工防护通常有哪些措施? 3.针对事件三中的不妥之处，分别写出正确做法，临时用电投入使用前，施工单位的哪些部门应参加验收 4.事件四中，按照《建筑业10 项新技术 (2010) 》规定，“钢筋及预应力技术”大项中，在本工程中可以推广与应用的新技术都有哪些? 5.指出事件五中施工单位做法不符合安全规定之处，并说明理由。在试吊时，必须进行哪些检查?
管内穿线有哪些要求?
翻译训练：大学生创业近年来大学生创业(entrepreneurship)问题越来越受到社会的关注,因为受过多年教育的大学生属于高级知识分子,他们背负着社会的种种期望。在社会经济繁荣发展的同时,大学生创业也成为新气象。现代大学生有创新精神,有对传统观念和传统行业挑战的信心和欲望,而这种创新精神也成为大学生创业的动力源泉,成为成功创业的信心基础。大学生怀揣创业梦想,努力打拼,实现自己的理想,证明自己的价值。
Without regular supplies of some hormones our capacity to behave would be seriously impaired; without others we would soon die. Tiny amounts of some hormones can modify moods and actions, our inclination to eat or drink, our aggressiveness or submissiveness, and our reproductive and parental behavior. And hormones do more than influence adult behavior; early in life they help to determine the development of bodily form and may even determine an individual’s behavioral capacities. Later in life the changing outputs of some endocrine glands and the body’s changing sensitivity to some hormones are essential aspects of the phenomena of aging. Communication within the body and the consequent integration of behavior were considered the exclusive province of the nervous system up to the beginning of the present century. The emergence of endocrinology as a separate discipline can probably be traced to the experiments of Bayliss and Starling on the hormone secretion. This substance is secreted from cells in the intestinal walls when food enters the stomach; it travels through the bloodstream and stimulates the pancreas to liberate pancreatic juice, which aids in digestion. By showing that special cells secret chemical agents that are conveyed by the bloodstream and regulate distant target organs or tissues. Bayliss and starling demonstrated that chemical integration could occur without participation of the nervous system. The term “hormone” was first used with reference to secretion. Starling derived the term from the Greek hormone, meaning “to excite or set in motion. The term “endocrine” was introduced shortly thereafter “Endocrine” is used to refer to glands that secret products into the bloodstream. The term “endocrine” contrasts with “exocrine”, which is applied to glands that secret their products though ducts to the site of action. Examples of exocrine glands are the tear glands, the sweat glands, and the pancreas, which secrets pancreatic juice through a duct into the intestine. Exocrine glands are also called duct glands, while endocrine glands are called ductless. 1.What is the author’s main purpose in the passage? A.To explain the specific functions of various hormones. B.To provide general information about hormones. C.To explain how the term “hormone” evolved. D.To report on experiments in endocrinology. 2.The passage supports which of the following conclusions? A.The human body requires large amounts of most hormones. B.Synthetic hormones can replace a person’s natural supply of hormones if necessary. C.The quantity of hormones produced and their effects on the body are related to a person’s age. D.The short child of tall parents very likely had a hormone deficiency early in life. 3.It can be inferred from the passage that before the Bayliss and Starling experiments, most people believed that chemical integration occurred only___. A.during sleep. B.in the endocrine glands. C.under control of the nervous system. D.during strenuous exercise. 4.The word “liberate” could best be replaced by which of the following? A.Emancipate B.Discharge C.Surrender D.Save 5.According to the passage another term for exocrine glands is___. A.duct glands B.endocrine glands C.ductless glands D.intestinal glands.
Dear Sir/Madam, I am pleased to write a letter of recommendation on behalf of Sand River and its CEO, Mrs. Jane King. I am very familiar with the company. My next book deals with it in detail, which is to be published in autumn of 2018. I am also familiar with European consumer. As a Dutch citizen, I have lived in Europe for 46 years and studied European consumer behavior for decades.I believe that Sand River offers something unique to the European market. It has established long-term supply relations with herdsman ( 牧民) families and owns advanced German machinery. Thus it combines natural resources with modern manufacturing techniques. But equally important, Sand River works with modern fashion designers to create truly contemporary and appealing designs. The result is a newly-established cashmere ( 羊绒) brand that appeals to a target group of high-income women. I met Mrs. King the first time in 2013. Since then, we have met several times and talked about Sand River's philosophy, strategy, and appeal to both Chinese and international consumers. I was struck by her deep knowledge about knitting (针织) technology, her enthusiasm for the brand, and her deep understanding of the cashmere shopper. I regard her as a "woman of her word." To summarize, I believe Sand River products deserve a place in luxurious European department stores and Mrs. King is a reliable partner. If you have any questions, please do not hesitate to contact me. Sincerely, Joan Smith 36、 Joan Smith wrote the recommendation letter on behalf of ______. A. a Dutch citizen B. herdsman families C. the European consumer D. Sand River and its CEO 37、 From the letter we can learn that Sand River ______. A. has long-term links with herdsmen B. employs many herdsman workers C. manufactures advanced machines D. sells hand-made products 38、 The target consumers of the newly-established cashmere brand are ______. A. college students B. blue-color workers C. high-income women D. average herdsman families 39、 By saying "a woman of her word" (Para. 3), the writer means that Mrs.King ______. A. always keeps her promise B. is a good public speaker C. knows customers well D. is well educated 40、 As far as the European market is concerned,the writer thinks that Sand River products ______. A. are fit for supermarkets in big cities B. are likely to enjoy a big market share C. will appeal to different kinds of customers D. deserve a place in luxurious department stores
Part III Cloze Directions: There are twenty blanks in the following passage. For each blank there are four choices. Choose the one that best fits into the passage and then marks your answer on the Answer Sheet. Before the 20th century the horse provided day to day transportation in the United States. Trains were used only for long-distance transportation. Today the car is the most popular 61 of transportation in all of the United States. It has completely 62 the horse as a means of everyday transportation. Americans use their cars for 63 90 percent of all personal 64 . Most Americans are able to 65 cars. The average price of a 66 made car was 1 050 in 1950, 1 740 in 1960 and up to 1 750 67 1975. During this period American car manufacturers set about 68 their products and work efficiency. As a result, the yearly income of the 69 family increased from 1950 to 1975 70 than the price of cars. For this reason 71 a new car takes a smaller 72 of a family’s total earnings today. In 1951 73 it took 8.1 months of an average family’s 74 to buy a new car. In 1962 a new car 75 8.3 of a family’s annual earnings. By 1975 it only took 4.75 76 income. In addition, the 1975 cars were technically 77 to models from previous years. The 78 of the automobile extends throughout the economy 79 the car is so important to Americans. Americans spend more money to 80 their cars running than on any other item. 61. A. kinds B. means C. mean D. types 62. A. denied B. reproduced C. replaced D. ridiculed 63. A. hardly B. nearly C. certainly D. somehow 64. A. trip B. works C. business D. travel 65. A. buy B. sell C. race D. see 66. A. quickly B. regularly C. rapidly D. recently 67. A. on B. in C. behind D. about 68. A. raising B. making C. reducing D. improving 69. A. unusual B. interested C. average D. biggest 70. A. slowest B. equal C. faster D. less than 71. A. bringing B. obtain C. bought D. purchasing 72. A. part B. half C. number D. side 73. A. clearly B. proportionally C. percentage D. suddenly 74. A. income B. work C. plans D. debts 75. A. used B. spend C. cost D. needed 76. A. months’ B. dollars C. family D. year 77. A. famous B. superior C. fastest D. purchasing 78. A. running B. notice C. influence D. discussion 79. A. then B. as C. so D. which 80. A. start B. leave C. keep D. repair