TEXT B
　　Social change is more likely to occur in heterogeneous societies than in homogeneous ones, simply because there are more diverse points of view available in the formers. There are more ideas, more conflicts of interest, and more groups and organizations of different persuasions. In addition, there is usually a greater worldly interest and tolerance in heterogeneous societies. All these factors tend to promote social change by opening more areas of life to decision rather than subjecting them to authority. In a quite homogeneous society- there are fewer occasions for people to perceive the need or the opportunity for change, because everything seems to be the same and. if not satisfactory, at least customary and undisputed.
　　Within a society, social change is also likely to occur more frequently and more readily (1) in the material aspects of the culture than in the non-material. for example, in technology rather than in values; (2) in what has been learned later in life rather than what was learned early: (3) in the less basic, less emotional, or less sacred aspects of society than in their opposites. like religion or a system of prestige: (4) in the simple elements rather than in the complex ones; (5) in form rather than in substance: and (6) in elements congenial to the culture rather than in strange elements.
　　Furthermore, social change is easier if it is gradual. For example, it comes more readily in human relations on a continuous scale rather than one with sharp dichotomies. This is one reason why change has not come more quickly to Black Americans as compared to other American minorities, because of the sharp difference in appearance between them and their white counterparts.

　　18. According to the passage, the main difference between a homogeneous society and a heterogeneous one lies in .
　　A. the number of opportunities offered
　　B. the nature of conflicts of interest
　　C. the awareness of the need for change
　　D. the role of social organizations

　　19. The author would most probably agree that changes are more likely to be successful in .
　　A. production methods B. ideological concepts
　　C. religious beliefs D. social behavior