【题目】Using traditional Chinese medical records, Youyou Tu rediscovered an ancient plant-based treatment for malaria that worked ________ modern therapies failed.
A. until B. unless C. although D. where
在线课程【答案】D
【解析】
试题分析：句意：根据中国传统的医学史料，屠呦呦再次发现了一种用古老的植物治疗疟疾的方法，现代医学(在此方面)都没有成功过。where在此处引导地点状语从句。故选D.