单选题 The dean tried to retain control of the situation on campus, but his attempt was ______ by the board of trustees.

【正确答案】 B

【答案解析】[解析] 动词词义辨析。根据句中转折连词but判定，空格应填入与tried to retain control(试图去控制)意思相对的词。选项中，frustrate(挫败，泄气)符合要求，意为“这些努力被大学董事会挫败”。故答案为B。