单选题   Human needs seem endless. They might be regarded as making up several levels. When there is enough money to satisfy one level of needs, another level appears:
    The first and most basic level of needs involves food. Once this level is satisfied, the second level of needs, clothing and some sort of shelter, appears. By the end of World War Ⅱ, these needs were satisfied for a great majority of Americans. Then a third level appeared. It included such items as automobiles and new houses.
    By 1957 or 1958 this third level of needs was fairly well satisfied. Then, in the late 1950s, a fourth level of needs appeared: the 'life-enriching' level. While the other levels involve physical satisfaction, that is, the feeding, comfort, safety, and transportation, this level stresses mental needs for recognition, achievement, and happiness. It includes a variety of goods and services. Among them are vacation trips, the best medical and dental care, and recreation. Also included here are fancy goods and the latest styles in clothing.
    On the fourth level, a lot of money is spent on services, while on the first three levels more is spent on goods.
    A fifth level would probably involve needs that can be achieved best by community action. Consumers may be spending more on taxes to pay for government action against disease, ignorance, crime, and prejudice. After filling our stomachs, our clothes closets, our garages, our teeth, and our minds, we now may seek to ensure the health, safety, and leisure to enjoy more fully the good things on the first four levels.

单选题     According to the passage, man will begin to think about such needs as housing and clothing only when ______.

单选题     It can be inferred from the passage that by the end of World War Ⅱ, most Americans ______.

单选题     What is the main concern of man on the fourth level?

单选题     The author tends to think that the fifth level ______.