31. Pewter, a metal with an ancient heritage, is still practical medium for the nonprofessional metalworker.
分析：可数名词前应有冠词或代词。(C)后的medium是可数名词，其前虽然有形容词practical，但缺乏冠词。应是still a practical…。
32. According to cognitive theories of emotion, anger occurs when individuals believe that A they have been harmed and that the harm was either avoidable and undeserved.
33. Jackie Mclean’s recordings have shown that he is one of the few jazz musicians who style A B of playing has kept pace with the evolution of modern jazz.
34. How Native Americans developed corn is a puzzling, for no wild corn has ever been discovered, and it grows only where people plant and tend it.
35. A principle of manager is to ensure that every action or decision achieves a carefully planned goal.