|
A rapid means of long-distance transportation became a necessity for the United States as settlement spread ever farther westward. The early trains were impractical curiosities, and for a long time the railroad companies met with troublesome mechanical problems. The most serious ones were the construction of rails able to bear the load, and the development of a safe, effective stopping system. Once these were solved, the railroad was established as the best means of land transportation. By 1860 there were thousands of miles of railroads crossing the eastern mountain ranges and reaching westward to the Mississippi. There were also regional southern and western lines. 38. The best title for this passage would be ________ A) Settlements Spread Westward B) The Coast-to-Coast Railroad: A Vital Link C) American Railroad History D) The Importance of Railroads in the American Economy 注：本文主题词：transcontinent railroad，A选项直接摘抄，C选项范围过大，D选项railroads范围过大 ●文章标题题型：1.文章主题词必须在选项中出现 2.选项范围恰如其分，不可过大，亦不可过于细节 范围过大：选项本身范围过大;选项缺少文章中的限定词 范围过细：只出现某一段中心事物的选项 | 
