he referred to in his article was unknown to the general reader.

 A. That                B. What             C. Whether          D. Where

______ he referred to in his article was unknown to the general reader.

  A. That            B. What              C. Whether               D. Where

______ he referred to in his article was unknown to the general reader.

  A. That      B. What          C. Whether            D. Where

The problem he referred to _____ difficult, but is isn’t at all.

A. must be     B. seeming      C. seems       D. seem

He referred his success ________ the good teaching he had had.

1. A.
   to
2. B.
   at
3. C.
   for
4. D.
   of