twice, the postman refused to deliver our letters unless we changed our dog
A. Being bitten
B. Bitten
C. Having bitten
D. To be bitten
网友回答
A. Being bitten
(答案→)B. Bitten
C. Having bitten
D. To be bitten
解析：考查分词的用法。The postman与bite之间是被动和完成的关系，所以答案为:B。