The coal miners     in the coal mine for 10 hours before we came to their rescue.

       A．had trapped                                       B．had been trapping

       C．had been trapped                                D．would have been trapped

The coal miners    in the coal mine for 10 hours before we came to their rescue.

1. A.
   had trapped
2. B.
   had been trapping
3. C.
   had been trapped
4. D.
   would have been trapped

The coal miners     in the coal mine for 10 hours before we came to their rescue.

       A．had trapped            B．had been trapping

       C．had been trapped            D．would have been trapped

The coal miners     in the coal mine for 10 hours before we came to their rescue.

A．had trapped                                              B．had been trapping

C．had been trapped                                     D．would have been trapped

The coal miners    in the coal mine for 10 hours before we came to their rescue.