上次提到了LBH12的练习，今天做了a，an，the的练习，这些练习在网上有程序可以做：Exercise 16.5.
错误的地方标示出来了：
From the native American Indians who migrate from Asia 20000 yeas ago to the new arrivals who come by planes, the Unite States is a nation of foreigners.
It is a country of immigrants who are living under single flag.
Back in the seventeenth and eighteenth centuries, at least 75% of the population came from England. However, between 1820 and 1975 more than 38 million immigrants came to this country from elsewhere in Europe. Many children of the immigrants were self-conscious and denied their heritage; many even refused to learn the native language of their parents and grandparents. They tried to “Americanize” themselves. The so-called Melting Pot theory of social change stressed importance of blending everyone together into a kind of stew. Each nationality would contribute its own flavor, but the final stew would be something called “American”.
The Melting Pot theory was never completely successful. In the last half of the twentieth century, an ethnic revival changed the metaphor. Many people now see American society as a mosaic. Americans are once again proud of their heritage, and ethnic differences make the mosaic colorful and interesting.
第一个”the” 因为native American Indians不是general的群体，而是群体的一部分 “who migrate from Asia 20000 yeas ago”