VOA慢速英语:透明国际：腐败仍然是非洲的一个问题

perception – n. the way you think about or understand something

index – n. a list or record of something

scale – n. a group of numbers that is used to show the size, strength, or quality of something — usually singular

audit – v. an official examination of one's behavior or activities

executive – n. a person who directs or supervises something; a directing or controlling office