23. Tom had to be told two or three times ________ he could remember what the teacher said.

A. before                      B. when             C. until               D. As

23. Tom had to be told two or three times ________ he could remember what the teacher said.

Tom had to be told two or three times ________ he could remember what the teacher said

1. A.
   before
2. B.
   when
3. C.
   until
4. D.
   As