- 2017年09月13日10:42 来源：小站整理
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Writing & Language
One of the primary shortcomings of the Homestead Act of 1862, a program through which the federal government offered free plots of land to US citizens willing to establish farms in the American West, was that the plots were too small to sustain a farm. Land in the semiarid Great Plains region received twenty or fewer inches of rain per year, so plots there were best left half unplanted each growing season to conserve water. With farms consisting of a mere 160 acres, however, this practice would not have produced sufficient harvests. Granted, raising cattle was impossible because the tiny homesteads would quickly become overgrazed. According to geologist and explorer John Wesley Powell, sustainable homesteads on the Great Plains actually needed to be a staggering 2,560 acres.
B.That is to say,
Choice D is the best answer because it provides the most logical transition between ideas, making clear that the point about the impossibility of raising cattle is provided as additional support for the paragraph's claim.
shortcoming ['ʃɔːtkʌmɪŋ] n. 缺点;短处
plot of land地块;基址
semiarid [,sem(a)ɪ'ærɪd] adj. 半干旱的;雨量非常少的
harvest ['hɑːvɪst] n. 收获;产量;结果 vt. 收割;得到 vi. 收割庄稼
overgraze [,əuvə'ɡreiz] vi. 过度放牧 vt. 在…上过度放牧
sustainable [sə'steɪnəb(ə)l] adj. 可以忍受的;足可支撑的;养得起的;可持续的