1、课文和练习5均选自An Outline of American History（《美国历史简介》）第七章GROWTH AND TRANSFORMATION，课文选自其中的“THE LAST FRONTIER ”；练习5选自其中的“REVOLUTION IN AGRICULTURE”。
2、The first great rush of population to the far west was drawn to the mountainous regions, where gold was found in California in 1848, in Colorado and Nevada 10 years later, in Montana and Wyoming in the 1860s, and in the Black Hills of the Dakota country in the 1870s.
这里的rush是指美国历史上有名的淘金热（the gold rush）。1848年，美国西部的加利福尼亚发现金矿，引起全国轰动。次年即有6－10万人涌向那里，掀起淘金热潮。但是，由于淘金热时期所发现的矿藏多为河水冲积而成的沙金，矿层很薄，开采量不大，且范围有限，因此，到1853年，加州各淘金点陆续枯竭，采矿业进入萧条期。1859年，内华达的康斯托克矿脉和科罗拉多州的派克山谷发现富矿，其金银等贵金属的蕴藏量为当时世界所罕见，兴起了第二次淘金热。但矿藏多半位于近千英尺的深层。不久，在这两大矿试行深层钻探获得成功，引发了采矿业的巨大变革。因而，急剧扩大了采矿业的范围。由于深层采矿需要大量资本和技术，因而，个人采矿逐渐被股份制企业采矿所代替，相应地，采矿业进入了工业性开采阶段。1875年以后发生于南达科他州的第三次淘金热，将西部人口增加到前所未有的数量，从1848年以前，不足50万人，到1910年几达3000万。
where gold was found in California in 1848, in Colorado and Nevada 10 years later, in Montana and Wyoming in the 1860s, and in the Black Hills of the Dakota country in the 1870s为非限制性定语从句，修饰the far west,非限制性定语从句（特别是较长的）的翻译一般采用分译法，并加词语，本句翻译时加“在那里”。
译文：大规模迁往极西地带的移民，大多集中在山区。在那里，加州于一八四八年发现了金矿，十年后在科罗拉多和内华达州，十九世纪六十年代，在蒙大拿和怀俄明州，十九世纪七十年代在达科他的黑山地区都先后发现了金矿。
类例：
1) I told the story to John, who told it to his brother.
   我把这件事情告诉了约翰，约翰又告诉了他的弟弟。
2) This is a college of science and technology, the students of which are trained to be engineers or scientists.
这是一所科技大学，该校学生将被培养成工程师或科学工作者。
3、permanent : lasting or intended to last for a long time or for ever
根据上下文，这里显然没有for ever 的意思，再说more, very等表示程度的词不能修饰表示极限的词，如round, perfect, permanent表示“for ever"时也同样由very修饰，所以，这里该词只有for a long time的意思，因此laid the foundations for more permanent settlements应译成“打下了长期居住的基础”。
理解原文是正确翻译的前提，同样这句中的open up the country根据上下文不能译成“打开这个国家”，而应该是“开发了这些地区”。Country: 地区（《新英汉词典》country : I.⑤（具有某中地理特点的）区域；地区；知识领域）
4、Eventually, though a few communities continued to be devoted almost exclusively to mining, the real wealth of Montana, Colorado, Wyoming, Idaho, and California proved to be in the grass and soil.
  Eventually: at last; in the end (esp .as a result) (Longman Dictionary of Contemporary English)
根据上文“有些移民已看到这些地区有从事农业和畜牧业的可能。”eventually译成“最后”或“结果”。
Almost exclusively:几乎专门
结果（最后）虽然少数城镇几乎专门从事采矿业，事实证明蒙大拿、科罗拉多、楼俄明、爱达荷等州的真正财富，也和加州一样，还是在草原和沃土中。
用增词法翻译proved“事实证明”，译文更贴切。
5、Cattle-raising, long an important industry in Texas, became even more flourishing after the war, when began to drive their Texas longhorns north across the open public domain.
the war: the American Civil War
enterprising men: the men who have the courage to do something daring or difficult
when : at that time
the open public domain: the public areas which are open to the all Americans
在得克萨斯州，养牛早就是重要行业，战后尤见繁荣，大胆的赶牛人赶着德州的长角牛，穿过开放的公共地带，向北走去。
这里across在英语里是介词，翻译成中文的动词，这是词类转译法，这符合英汉语言的差异（见L4学习指导6）。类例：
I barreled straight ahead, across the harbour and out over the sea.
我笔直向前高速飞行，越过港口，飞临海面。
6、for hundreds of kilometers, trails were dotted with herds of cattle moving northward.
《英汉双解剑桥国际英语词典》这样解释be dotted with的：When an area is dotted with things, it has many of them in different places.
例如：The countryside is dotted with beautiful ancient churches.
   郊区分布着许多美丽的古老教堂。
句子可译成：向北迁移的牛群，在几百公里的征途上到处可见。
7、Altogether, between 1866 and 1888, some six million head of cattle were driven up from Texas to winter on the high plains of Colorado, Wyoming, and Montana.
在一八六六年至一八八八年间，总共大约有六百万头牛从德州放牧到科罗拉多、怀俄明、蒙大拿等地的高原上过冬。
some = about 
Altogether修饰数字，意思是“总共”
some six million head of cattle were driven up from Texas to winter on...
这是一句被动结构的句子，译成汉语主动句，原文中的主语在译文中仍作主语，这是英语被动句翻译方法之一。类例：
1) The whole country was armed in a few days.
   几天以内全国武装起来了。
2) The sense of inferiority that he acquired in his youth has never been totally eradicated.
   他在青少年时期留下的自卑感，还没有完全消除。
8、The cattle boom reached its height by 1885,
    “养牛业兴旺发达，到一八八五年已达到最高峰”比“养牛业的兴旺发达，到一八八五年已到达最高峰”似乎更符合中文习惯。第一、后者太拘于原文the cattle boom这个偏正结构，事实上，在这种情况下，中文更多用主谓结构。第二、我们往往说“达到...程度”和“到达...地点”。
9、then the range became too heavily pastured to support the long drive, and was beginning to be criss-crossed by railroads.
then: after that
pasture: (here) put the cattle in a land where the cattle feed on the growing grass
too...to...太...以致...
crisscross: vt. 在...上交叉往来
译文：
   从那以后，草原由于过多的放牧，已经不足以供这些“长途迁移”的牛群吃草的需要了，并且也开始被纵横交错的铁路线所割裂。
10、Not far behind the rancher creaked the prairie schooners of the farmers bringing their families, their draft horses, cows, and pigs.
   句子因否定词放句首加上主语太长而倒装，主语为the prairie schooners11 of the farmers bringing (=who were bringing) their families, their draft horses, cows, and pigs，修饰farmers的定语可以采用分译法。
    schooners: [美]有篷四轮大马车
译文：
   在牧牛人身后不远之外，有许多草原篷车在吱吱作响，农民把他们的妻儿，还有拉车的马、乳牛和猪群也带了来。
11、Under the Homestead Act they staked their claims and fenced them with barbed wire. Ranchmen were ousted from lands they had roamed without legal 单元内容浏览. Soon the romantic "wild west" had ceased to be.
译文：
   根据“宅地法”，他们圈定了所得的土地，并用铁丝网围起来。原来未经合法手续取得土地的牧牛人都被赶了出去。不久，这片具有浪漫气氛的“西部荒原”，便不复存在了。
barb:装倒刺于...；barbed wire有刺铁丝网
had ceased to be = no longer existed