听力原文：M: Professor, bow's Chinese Americans' situation today? F: There are fewer than half a million, only a small fraction of the U.S. population, living chiefly in California, New York, and Hawaii. But they are generally admired for their many remarkable characteristics, and are often held up as an example worth following. M: When, then, did things begin to change? F: It was during World War II, when China was an ally of the United States. The Exclusion laws were ended; in 1965, in a general revision of the immigration laws, many more Chinese were permitted to settle here, as discrimination against immigration was abolished. M: But it seemed that the Chinese had lived apart in their own separate neighborhoods, which came to be known as 'Chinatowns'. F: Right. And in each of them the residents organized an unofficial government to make rules for the community and to settle disputes. To this day, certain Chinatowns, especially those of Francisco and New York, are busy, thriving communities. M: Professor, there are two facts about the Chinese Americans: one is that there is so little juvenile delinquency among them; the other is that there are so many outstanding scholars, scientists, and artists out of their uneducated laborers ancestors. How can we explain these? F: Well, we may owe little juvenile delinquency to their retaining many aspects of their ancient culture. For example, their family ties continue to be remarkably strong. Even young children cherish the old values and attitudes, including respect for their elders and a feeling of responsibility to the family. Secondly, the high regard for education which is deeply imbedded in Chinese culture, and the willingness to work very hard to gain advancement, are other noteworthy characteristics of theirs. This explains why so many descendants of laborers have succeeded in becoming doctors, lawyers, and other professionals. How many Chinese Americans are there in the U.S. today?