单选题 In a sample of associates at a law firm, 30 percent are second-year associates, and 60 percent are not first-year associates. What percentage of the associates at the law firm have been there for more than two years?
A. 10
B. 20
C. 30
D. 40
E. 50

【正确答案】 C

【答案解析】The answer must be a subset of the 60 percent of associates that are not first-year associates. Of these, you must subtract the 30 percent that are second-year associates, leaving only 30 percent, so the answer is C.