[填空题]In the United States influenza is one of the ten principle causes of death.

The United States counts its population every ten years, and each census reveals that the racial and ethnic mix is changing dramatically, so by the year 2050, the "average" American will not be descended from (1)  , but the majority of U. S. residents will trace (2)  ancestry to Africa, Asia, the Hispanic world, the Pacific Islands, or the Middle East. Once the United States was a microcosm of European nationalities, (3)  the United States is a microcosm of the world. The United States is (4)  considered a "melting pot" society by many of its residents. (5) , many people prefer the term "salad bowl." They use this (6)  to describe American society. American society will soon be (7)  nonwhite. "Melting pot" implies that the different ethnic groups blend together (8)  one homogeneous (9) , "salad bowl" (10)  that nationalities, like the ingredients in a mixed green salad, retain their cultural