_____twice, the postman refused to deliver our letters unless we chained our dog.

_____twice, the postman refused to deliver our letters unless we chained our dog.

_____twice, the postman refused to deliver our letters unless we chained our dog.

_____twice, the postman refused to deliver our letters unless we chained our dog.

     twice, the postman refused to deliver our letters unless we chained our dog.

       A．Being bitten        B．Bitten                 C．Having bitten       D．To be bitten

_____twice, the postman refused to deliver our letters unless we chained our dog.

     twice, the postman refused to deliver our letters unless we chained our dog.

       A．Being bitten    B．Bitten       C．Having bitten   D．To be bitten

     twice, the postman refused to deliver our letters unless we chained our dog.

A．Being bitten          B．Bitten    C．Having bitten          D．To be bitten

______ twice, the postman refused to deliver our letters unless we chained our dog.

A．Being bitten         B．Bitten         C．Having bitten         D．To be bitten

_____twice, the postman refused to deliver our letters unless we chained our dog.