When I worked as the general manager of the firm, I sometimes had to visit London on business.
A. opportunity
B. possibility
C. occasion
D. chance
网友回答
A. opportunity
B. possibility
(答案→)C. occasion
D. chance
解析： occasion 作可数名词时，意为“时机”，作不可数名词时，意为“必要”，本题中occasion意为“必要”。从句语法结构上看，本句中用opportunity(难得的)机会，chance（偶然的）机会均可，但按逻辑意思，应用occasion.