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
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
D