It was such a difficult problem ________ few students in our class worked out．

1. A.
   that
2. B.
   what
3. C.
   as
4. D.
   which

It was such a difficult problem_______ few students in our class worked out．

       A．that   B．what        C．as      D．which

It was such a difficult problem_______ few students in our class worked out．

A．that         B．what         C．as          D．which