A) Theories are simply imaginary models of past events.examda

　　B) It is better to revise a hypothesis than to reject it.

　　C) A scientist's most difficult task is testing hypotheses.

　　D) A good scientist needs to be creative.

　　B) Education systems need to be radically reformed.

　　C) Going to school is only part of how people become educated.

　　D) Education involves many years of professional training.

　　20. The passage is organized by ___

　　A) listing and discussing several educational problems

　　B) contrasting the meanings of two related concepts

　　C) narrating a story about excellent teachers

　　D) giving examples of different kinds of schools