题目内容：
Questionsare based on the following passage.Many current discussions of immigration issues talk about immigrants in general, as if they were abstract people in an abstract world. But the concrete differences between immigrants from different countries affect whether their coming here is good or bad for the American people.
The very thought of formulating immigration laws from the standpoint of what is best for the American people seems to have been forgotten by many who focus on how to solve the problems of illegallymmigration.
It is hard to look for "the ideal outcome" on immigration in the abstract. Economics professor Milton Friedman once said, "The best is the enemy of the good," which to me meant that attempts to achieve an unattainable ideal can prevent us from reaching good outcomes that are possible in practice. Too much of our current immigration controversy is conducted in terms of abstract ideals, such as
"We are a nation of immigrants." Of course we are a nation of immigrants. But we are also a nation of people who wear shoes. Does it follow that we should admit anybody who wears shoes?
The immigrants of today are very different from those who arrived here a hundred years ago. Moreover, the society in which they arrive is different. To me, it is better to build a wall around the welfare state than the country.
But the welfare state is already here--and, far from having a wall built around it, the welfare state is expanding in all directions. We do not have a choice between the welfare state and open borders. Anything we try to do as regards immigration laws has to be done in the context of a huge welfare state that is already a major, inescapable fact of life.
Among other facts of life utterly ignored by many advocates of de facto amnesty (事实上的大赦) is that the free international movement of people is different from free international trade in goods.
Buying cars or cameras from other countries is not the same as admitting people from those countries or any other countries. Unlike inanimate objects, people have cultures and not all cultures are compatible with the culture in this country that has produced such benefits for the American people for so long.
Not only the United States, but the Western world in general, has been discovering the hard way that admitting people with incompatible cultures is an irreversible decision with incalculable consequences. If we do not see that after recent terrorist attacks on the streets of Boston and London, when will we see it?"Comprehensive immigration reform" means doing everything all together in a rush, without time to look before we leap, and basing ourselves on abstract notions about abstract people.
What does the author say about immigrants in America? A．They all hope to gain citizenship and enjoy the welfare.
B．They come to America with different dreams and purposes.
C．Their background may determine whether they benefit the American people.
D．Their cultures affect the extent to which they will achieve success in America.
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