These doctors are busy day and night, a cure for AIDS.
A. bringing on
B. pulling on
C. taking on
D. working on
网友回答
A. bringing on
B. pulling on
C. taking on
(答案→)D. working on
解析：动词短语辨析。bring on引起, 使发展, 提出；穿上；pull on继续拉；穿上；take on雇佣，呈现，承担；work on从事于，进行；句意：那些医生日夜忙碌，进行对艾滋病的治疗。