68. By saying "the brain at any age is highly plastic ", the writer probably means the brain can be______. (A) used (B) mastered (C) developed (D) researched

74. The writer's purpose in mentioning The Republic is to________. (A) explain why it was included in the list (B) describe why he seriously crossed it off the list (C) show that he read the books blindly though they were hard to understand (D) prove that he understood most of it because he had looked at every word