Translate the following paragraph into Chinese. The American Dream is a national ethos( 精神特质 )of the United States. The term is used in many ways, but it essentially is an idea that suggests that anyone in the US can succeed through hard work and has the potential to lead a happy, successful life. Many people have expanded upon or refined the definition to include things such as freedom, fulfillment and meaningful relationships. The idea of an American Dream is older than the US, dating back to the 1600s, when people began to have all sorts of hopes and aspirations for what was a new and largely unexplored continent to European immigrants. And the meaning of the Dream has changed over the course of history, including both personal components and a global vision. But not everybody thinks the American Dream is a positive thing. Some people believe that the structure of society in the US prevents such an idealistic goal for everyone. Critics often point to examples of inequality rooted in class, race, religion and ethnicity that suggest that the American Dream is not attainable for everyone.