Oil Refining
An important new industry, oil refining, grew after the Civil War. Crude oil, or petroleum -- a dark, thick ooze from the earth -- had been known for hundreds of years, but little use had ever been made of it. In the 1850s Samuel M. Kier, a manufacturer in western Pennsylvania, began collecting the oil from local seepages and refining it into kerosene. Refining, like smelting, is a process of removing impurities from a raw material. Kerosene was used to light lamps. It was a cheap substitute for whale oil, which was becoming harder to get. Soon there was a large demand for kerosene. People began to search for new supplies of petroleum. The first oil well was drilled by E. L. Drake, a retired railroad conductor. In 1859 he began drilling in Titusville, Pennsylvania. The whole venture seemed so impractical and foolish that onlookers called it Drakes Folly. But when he had drilled down about 70 feet , Drake struck oil. His well began to yield 20 barrels of crude oil a day. News of Drakes success brought oil prospectors to the scene. By the early 1860s these wildcatters were drilling for black gold all over western Pennsylvania. The boom rivaled the California gold rush of 1848 in its excitement and Wild West atmosphere. And it brought far more wealth to the prospectors than any gold rush. Crude oil could be refined into many products. For some years kerosene continued to be the principal one. It was sold in grocery stores and door-to-door. In the 1880s refiners learned how to make other petroleum products such as waxes and lubricating oils. Petroleum was not then used to make gasoline or heating oil.
表示原因关系的连词
目的状语从句
had better的用法
表示转折或对比
will和would的区别
否定转移的应用
定语从句的概念
as, which 非限定性定语从句
must表示推测的用法
表示"一…就…"的结构
结果状语从句
情态动词的回答方式
原因状语从句
并列连词与并列结构
比较may和might
名词性从句的概念
引导名词性从句的连接词
关系代词引导的定语从句
先行词和关系词二合一的应用
if only和only if 的区别
关系副词引导的定语从句
条件状语从句
地点状语从句
so和such的区别
判断关系代词与关系副词
情态动词的语法特征
would rather的用法
比较while, when, as
连词的概念
情态动词表示推测的用法
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