【题目】The doctor said jokingly that his own infection of the virus _____ the discovery of a vaccine (疫苗)of the disease.
A. stood for B. called for
C. paid for D. contributed to
在线课程【答案】D
【解析】短语辨析。A.代表 B. 呼吁 C. 为……付出代价 D.导致。句意：医生开玩笑的说，他自己被病毒的感染导致发现了这种病毒的疫苗。故选D。