--- Do you doubt ____ he’ll be fired by the school?    
--- No, not a bit. But I doubt ____ he will bury himself into study.

I doubt _______ he will win or not.

I doubt______ he will come to attend our school’s 107^th anniversary ceremony.

1. A.
   that
2. B.
   whether
3. C.
   what
4. D.
   how

--- Do you doubt ____ he’ll be fired by the school?    

--- No, not a bit. But I doubt ____ he will bury himself into study.

A．that; that          B．whether; /         C．if ; that           D．that; whether

I doubt _______ he will win or not.

A．whether          B．if                C．that              D．when