单选题
Despite repeated ______ by educational authorities for concrete measures to reduce students' burdens, little has changed.
【正确答案】
D
【答案解析】[分析] 名词辨析
A．directions指示，用法，说明；B．recommendations推荐，介绍，劝告；C．advice忠告，建议；D．calls召唤，呼吁，号召，拜访；而本句意为：尽管教育界的权威人士一再号召采取具体措施来减轻学生负担，一切还是老样子。因此D为答案。