Twenty-three hours has passed after the explosion in the mine，but rescue efforts to recover the missing ________ carried out．

1. A.
   are still being
2. B.
   have already
3. C.
   are now
4. D.
   will soon be

Twenty-three hours has passed after the explosion in the mine，but rescue efforts to recover the missing ________ carried out．

A．are still being

B．have already

C．are now

D．will soon be