The railroads【C1】______ a key role in the settlement of the West. They provided relatively

easy【C2】______ to the region for the first time, and they also actively received farmers to settle there. The railroads are criticized【C3】______ their part in settling the West too rapidly.【C4】______ , there were abuses【C5】______ with building and operating the railroads, but it must be pointed out that they performed a useful service in【C6】______ the frontier and helping to achieve national【C7】______ .

The real tragedy of the rapid settlement of the Great Plains 【C8】______ the shameful way in which the American Indians were treated. Threatened with the destruction of their whole【C9】______ of life, the Indians fought back savagely【C10】______ the white man's final thrust(强行推进). Justice was almost entirely 【C11】______ the Indians' side. The land was clearly theirs; frequently their title was legally【C12】______ by a treaty negotiated with the federal government. The Indians,【C13】______ , lacked the military force and political power to protect this right. Not only did white men encroached 【C14】______ the Indians' hunting ground, but they rapidly destroyed the Indians' principal【C15】______ of existence--the buffalo. It has been【C16】______ that some 15 million buffalo roamed the plains in the 1860s. By 1869 the railroads【C17】______ the herd in half, and by 1875 the southern herd was 【C18】______ eliminated. By the middle of the 1880s the northern herd was also a thing of the past. Particularly irritating to the Indians was the fact【C19】______ the white man frequently killed the buffalo merely for sport, leaving the valuable animal to rot【C20】______ .

【C1】

A．functioned

B．played

C．had

D．took