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One of the most famous bridges in the world is the Golden Gate Bridge that spans San Francisco Bay. Because it was built in 1937, it has become one of the first sights people see if they are coming to San Francisco by ship. The main part of the Golden Gate Bridge is a suspension span. It hangs from steel cables that are supported by two huge towers, one at each end of the bridge. The suspension span was the longest in the world when it was finished in 1937. It measures 4,200 feet between the towers. The floor of thebridge is wide enough for six lanes of cars, three in each direction. There are sidewalks, too, but not many people use them. It costs a lot of time to go on foot from one end of the bridge to the other.The years since 1950 have been called the era of the giant bridge. Most of them have been built in the United States. The Mackinac Bridge in upper Michigan was finished in 1958. It is a suspension bridge, with foundations resting on rock 200 feet below the surface of the water. With a span of 3,800 feet, it was the second in length to the Golden Gate Bridge.In 1964 the longest and heaviest suspension bridge was completed in New York City. Known as the Verrazano--Narrows Bridge, it carries traffic between Staten Island and Brooklyn, parts of the city of New York. Before it was built, commuters to the city had to travel by ferry. Now millions of cars pass over the bridge every year. When a lower deck is added, 48 million cars will be able to cross the bridge in a single year. What is the main part of the Golden Gate Bridge
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Predictions of many robots in industry have yet come true. For ten years or more, manufacturers of big robots have explained how their machines can make industry more competitive and productive. The maker for (21) robots is oversupplied now, and the driving force of the robotics(机器人学) revolution is (22) to be with makers of machines that handle a few kilos at most."Heavy-robot manufacturers are in some difficulty (23) finding customer. They are offering big (24) just to get in the door. There has been a (23) growth everywhere in the numbers of robots, so we admit we are either deceiving (26) or that the market is slowly growing. "said John Reekie, chairman of Colen Robotics. "The following things must happen (27) the robotics revolution to occur. We must achieve widespread robot literacy, (28) there has been a computer (29) program, there must be a robot prices. (30) , some kind of artificial intelligence needs to be (31) ."Colen makes educational robots and machine tools. It is small (32) with companies like ASEA or Fujitsu Fanuc. But Colen with others and departments in universities such as Surrey, Manchester, and Durham possess an advantage (33) . the giants. The big companies sell very expensive (34) to businesses with expert knowledge in automation. The (35) companies make robots for teaching people, and now they have realized that there is a need for small, (36) robots that they can meet.The little companies either bring their educational machines (37) an industrial standard or design from the start. One technique that they all adopt is to choose (38) components where possible. The major cost of making (39) their models is the electronics, which will fall in price. There is (40) scope for reductions in mechanical costs. The sue of standard parts, which are easily replaced, should give these robots a mechanical life of something in the order of five years. 34().
什么是结构的极限状态说明如何分类及具体的状态要求。
In the 18th century, New York was smaller than Philadelphia and Boston. Today it is the largest city in America. How to explain the change in its size and importanceTo answer this question we must consider certain facts about geography, history and economies. Together these three will explain the huge growth of America’s most famous city.The map of the Northeast shows that four of the most heavily-populated areas in this region are around seaports. At these points materials from across the sea enter America, and the products of the land are sent there for export across the sea.Economists know that places where transportation lines meet are good places for making raw materials into completed goods. That is why seaports often have cities nearby. But cities like New York needed more than their geographical location in order to become great industrial centers. Their development did not happen simply by chance.About 1815, when many Americans from the east coast had already moved to the west, trade routes from the ports to the central regions of the country began to be a serious problem. The slow wagons of that time, drawn by horses or oxen, were too expensive for moving heavy freight very far. Americans had long admired Europe’s canals. In New York State a canal seemed the best solution to the transportation problem. From the eastern end of Lake Erie all the way across the state to the Hudson River there is a long trip of low land. Here the Erie Canal was constructed. After working for several years it was completed in 1825.The canal produced an immediate effect. Freight costs were cut to about one-tenth of what they had been. New York City, which had been smaller than Philadelphia and Boston, quickly became the leading city of the coast. In later years, transportation routes on the Great Lakes were joined to routes on the Mississippi River. Then New York City became the end point of a great inland shipping system that extended from the Atlantic Ocean far up the western branches of the Mississippi.The new railroads made canal shipping not as important as before, but it tied New York even more closely to the central regions of the country. It was easier for people in the central states to ship their goods to New York for export overseas.Exports from New York were greater than imports. Consequently, shipping companies were eager to fill their ships with passengers on the return trip from Europe. Passengers could come from Europe very cheaply as a result.Thus New York became the greatest port for receiving people from European countries. Many of them remained in the city. Others stayed in New York for a few weeks, months, or years, and then moved to other parts of the United States. For these great numbers of new Americans, New York had to provide homes, goods, and services. Their labor helped the city become great. Which of the following respects does NOT help New York become the most famous city()
Predictions of many robots in industry have yet come true. For ten years or more, manufacturers of big robots have explained how their machines can make industry more competitive and productive. The maker for (21) robots is oversupplied now, and the driving force of the robotics(机器人学) revolution is (22) to be with makers of machines that handle a few kilos at most."Heavy-robot manufacturers are in some difficulty (23) finding customer. They are offering big (24) just to get in the door. There has been a (23) growth everywhere in the numbers of robots, so we admit we are either deceiving (26) or that the market is slowly growing. "said John Reekie, chairman of Colen Robotics. "The following things must happen (27) the robotics revolution to occur. We must achieve widespread robot literacy, (28) there has been a computer (29) program, there must be a robot prices. (30) , some kind of artificial intelligence needs to be (31) ."Colen makes educational robots and machine tools. It is small (32) with companies like ASEA or Fujitsu Fanuc. But Colen with others and departments in universities such as Surrey, Manchester, and Durham possess an advantage (33) . the giants. The big companies sell very expensive (34) to businesses with expert knowledge in automation. The (35) companies make robots for teaching people, and now they have realized that there is a need for small, (36) robots that they can meet.The little companies either bring their educational machines (37) an industrial standard or design from the start. One technique that they all adopt is to choose (38) components where possible. The major cost of making (39) their models is the electronics, which will fall in price. There is (40) scope for reductions in mechanical costs. The sue of standard parts, which are easily replaced, should give these robots a mechanical life of something in the order of five years. 25().
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