2. What is the purpose of the statement, “Whereas in 1810 only a seventh of the American people lived west of the Appalachian Mountains, by 1840 more than a third lived there”?
从1810到1840，短短30年，体现速度之快(speed)；
从1/7变成1/3美国人住在西部，体现迁移涉及人口之多(range)。
- To illustrate that generally population shifts occur rapidly
- To correct a mistaken impression of American agriculture from 1810 to 1840
- To emphasize the range and speed with which the westward migration occurred
- To demonstrated how attractive the Appalachian Mountains were to Americans
4. According to paragraph 2, all of the following are reasons why Americans migrated westward EXCEPT 美国人向西迁徙的原因
- the desire to move from one place to the next
A选项对应原文：restless, rootless, ambitious 与 the nomadic and daring settlers
- the hope of improving their socioeconomic status
- the opportunity to change jobs
BC选项对应原文：
In American society, however, the class structure was less rigid; some people changed occupations easily and believed it was their duty to improve their social and economic position.
…in search of new homes, material sccess, and better lives
- the need to escape religious or political crises 张冠李戴
D选项是欧洲人离开欧洲的原因，不是美国人西进的原因。
属于典型的偷换对象、张冠李戴错误。
原文依据：The European ancestors of some Americans had for centuries lived rooted to the same village or piece of land until some religious, political, or economic crisis uprooted them and drove them across the Atlantic.