13.The development of the railroad and telegraph systems during the middle third of the nineteenth century led to significant improvements in the speed, volume, and regularity of shipments and communications, making possible a fundamental transformation in the production and distribution of goods.

　　雅思在第三个十九世纪中期铁路和电报系统的发展导致了在速度、音量和普通的船运和通讯上的明显的进步，使生产和分发货物方面的一个基础的转变有可能发生。

　　14.Add to this the timidity with which unschooled artisans – originally trained as stonemasons, carpenters, or cabinetmakers – attacked the medium from which they were to make their images, and one understands more fully the development of sculpture made in the United States in the late eighteenth century.

　　由于未受学校教育的艺术家们的胆却，他们通常被训练成石匠、木匠或家具师， 抨击了在媒体中他们以前造就的自我形象和一个理解，这个理解就是雕塑的发展在十八世纪晚期的美国更加完全的发生了。

　　15.Instead of trying to keep down the body temperature deep inside the body, which would involved the expenditure of water and energy, desert mammals allow their temperatures to rise to what would normally be fever height, and temperatures as high as 46 degrees Celsius have been measured in Grant’s gazelles.

　　除了尽量去保持身体深处的低体温，这将包括支出水和能量，沙漠哺乳动物们允许他们的温度上升到一个通常来说是发烧的温度并且温度高达46摄氏度，这已被在格兰特瞪羚测得。

　　16.Solitary roosters shelter in dense vegetation or enter a cavity – horned larks dig holes in the ground and ptarmigan burrow into snow banks – but the effect of sheltering is magnified by several birds huddling together in the roots, as wrens, swifts, brown creepers, bluebirds, and anis do.

　　孤独的雄鸡躲避在茂盛的植被下或进入洞穴躲藏，如角状的百灵在地面挖洞躲藏和松鸡在雪岸挖洞躲藏，但是象鹪鹩、雨燕、褐色的爬行动物、蓝知更鸟和anis所做的一样，由于多只鸟一起拥挤在根茎下，所以躲避的效果被扩大。

　　17.Each SMSA would contain at least (a) one central city with 50000 inhabitants or more or (b) two cities having shared boundaries and constituting, for general economic and social purposes, a single community with a combined population of at least 50000, the smaller of which must have a population of at least 15000.

　　每个大城市及其郊区至少能容纳(a)一个5000居民人口的中心城市或(b)为了一个普通的经济和社会目的共享边界和律法的两个城市，一个单个的融合的社区人口至少50000，更小一点的社区必须有至少15000人口。