| For centuries, explorers have risked
their lives venturing into the unknown for reasons that were to varying degrees
economic and nationalistic. Columbus went west to look for better trade routes
to the Orient and to promote the greater glory of Spain. Lewis and Clark
journeyed into the American wilderness to find out what the U.S. had acquired
when it purchased Louisiana, and the Appolo astronauts rocketed to the moon in a
dramatic show off technological muscle during the cold war. Although their missions blended commercial and political-military imperatives, the explorers involved all accomplished some significant science simply by going where no scientists had gone before. Today Mars looms (隐约出现) as humanity’s next great terra incognita (未探明之地). And with doubtful prospects for a short-term financial return, with the cold war a A. To find out if life ever existed there. B. To see if humans could survive there. C. To prove the feasibility of large-scale space ventures. D. To show the leading role of science in space exploration. [单选题]GPON网络中，接入层的覆盖半径为:
A.10KM B.5.5KM C.15KM D.20KM [填空题]防止钢筋锈蚀最重要的措施是增加混凝土的（）和混凝土的（）。
[单项选择]青霉素过敏性休克时，首选何药抢救：
A. 多巴胺 B. 去甲肾上腺素 C. 肾上腺素 D. 葡萄糖酸钙 [单选题]中国梦与世界各国人民的美好梦想息息相通，主要体现在（ ）。
A.中国梦是国家梦、民族梦和人民的梦 B.中国梦是改革梦和开放梦 C.中国梦是历史的、现实的和未来的 D.中国梦是和平、发展、合作、共羸的梦 [单选题]下列( )不是举高消防车200小时保养的项目。（中）
A. 调试检查所有安全限制保护装置的功能是否正常，发现问题及时修复。 B. 清洗液压系统液压油箱、滤网及污物收集器，更换破损的滤芯或已堵塞的纸质滤芯。 C. 目测检查伸缩臂限制开关的基本情况，是否紧固，是否清洁，并可作一定的调整。 D. 调试检查应急汽油发动机应急操作系统功能是否正常，发现问题及时修复。 [单项选择]由磁控管作为振荡器的发射机类属于（）。
A. 主振放大式发射机 B. 刚性开关脉冲调制器发射机 C. 软性开关脉冲调制器发射机 D. 单级振荡式发射机 [单项选择]用不在一直线上的三点可确定刚体在空间的位置，而每个点有三个坐标（即有三个运动方程），欲确定平移刚体在空间的运动需要几个运动方程（坐标）（）。
A. 3个 B. 6个 C. 9个 D. 5个 [多项选择]Comparisons were drawn between the development of television in the 20th century and the diffusion of printing in the 15th and 16th centuries. Yet much had happened (1) As was discussed before, it was not (2) the 19th century that the newspaper became the dominant pre-electronic (3) , following in the wake of the pamphlet and the book and in the (4) of the periodical. It was during the same time that the communications revolution (5) up, beginning with transport, the railways and leading (6) through the telegraph, the telephone, radio, and motion pictures (7) the 20th century world of the motor car and the airplane. Not everyone sees that process in (8) . It is important to do so.
It is generally recognized, (9) , that the introduction of the computer in the early 20th century, (10) by the invention of the integrated circuit during the 1960s, radically changed the process, (11) it A. unless B. since C. lest D. although [单选题]在《民用航空空中交通管理运行单位安全管理规则》中规定，民航空管运行单位应当按照（），确立民航空管运行安全指标。
A.民航空管安全绩效 B.民航安全绩效 C.民航空管安全目标 D.民航安全目标 我来回答: 提交
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