streets by as much as 12 feet.

　　This of course created a new problem: dirt practically buried the first floors of every building in Chicago. Building owners were faced with a choice: either change the first floors of their buildings into basements, and the second stories into mainfloors, or hoist(吊起) the entire buildings to meet the new street level. Small wood­frame buildings could be lifted fairly easily. But what about large, heavy structures like the Tremont Hotel, which was a six­story brick building?

　　That's where George Pullman came in. He had developed some house­moving skills successfully. To lift a big structure like the Tremont Hotel, Pullman would place thousands of jackscrews(螺旋千斤顶) beneath the building's foundation. One man was assigned to operate each section of roughly 10 jackscrews. At Pullman's sign each man turned his jackscrews by the same amount at the same time, thereby raising the building slowly and evenly. Astonishingly, the Tremont Hotel stayed open during the entire operation, and many of its guests didn't even notice anything was happening. Some people like to say that every problem has a solution. But in Chicago's early history, every engineering solution seemed to create a new problem. Now that Chicago's waste water was draining efficiently into the Chicago River, the city's next step was to clean the polluted river.

　　语篇导读　本文主要介绍了芝加哥为了应对洪水泛滥的问题而实行的一些解决方案。

　　5．The author mentions the joke in Paragraph 1 to show ________.

　　A．horses were fairly useful in Chicago

　　B．Chicago's streets were extremely muddy

　　C．Chicago was very dangerous in the spring

　　D．the Chicago people were particularly humorous

　　解析　B　写作意图题。根据第一段第一句可推知，作者提及这个笑话是为了表明芝加哥的街道曾经非常泥泞，故选B项。

　　6．The city planners were convinced by Ellis Chesbrough to ________.

　　A．get rid of the street dirt B．lower the Chicago River

　　C．fight against heavy floods D．build the pipes above ground

　　解析　D　细节理解题。根据第三段第一句可知，Ellis Chesbrough让城市规划者相信在地上建管道才能解决洪水泛滥带来的问题，故选D项。

　　7．What can we conclude about the moving operation of the Tremont Hotel?

A．It went on smoothly as intended.