A

　　In its early history, Chicago had floods frequently, especially in the spring, making the streets so muddy that people, horses, and carts got stuck. An old joke that was popular at the time went something like this: A man is stuck up to his waist in a muddy Chicago street. Asked if he needs help, he replies, "No, thanks. I've got a good horse under me."

　　The city planner decided to build an underground drainage (排水) system, but there simply wasn't enough difference between the height of the ground level and the water level. The only two options were to lower the Chicago River or raise the city.

　　An engineer named Ellis Chesbrough convinced me the city that it had no choice but to build the pipes above ground and then cover them with dirt. This raised the level of the city's 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 main floors, or hoist the entire buildings to meet the new street level. Small wood-frame buildings could be lifted fairly easily. But what about large, heavy structures like Tremont Hotel, which was a six-story brick building?

　　That's where George Pullman came in. He had developed some house-moving 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

【2016届高三英语二轮复习作业卷：17（含解析）（河北衡水）】相关文章：

★ 【课堂新坐标】2017届高考英语（通用版）二轮复习完形填空专题训练：技法1 利用上下文暗示解题（含解析）

★ 【北师大版】2014届高考英语一轮复习指导课时作业：Unit 11 A卷 Word版含解析

★ 2014届高考英语一轮复习选修8参考答案（外研版）

★ 2017届高考英语二轮复习课时训练：21（含解析）

★ 2014届高考英语一轮复习课时作业(十二)必修2Module 6《Films and TV Programmes》（外研版）

★ 2017高考四川省广安市英语阅读理解一轮系列训练：7（含解析）

★ 2017年高考英语二轮复习精品资料：专题16 书面表达（押题专练）（原卷版）

★ 四川省2016届高考英语一轮复习课时作业（42） Module 6 The World’s Cultural Heritage 外研版选修8

★ 2014届高考英语一轮复习课时作业(十九)必修4Module 1《Life in the Future》（外研版）

★ 【北师大版】2014届高考英语一轮复习指导课时作业：Unit 7 A卷 Word版含解析