I am ashamed, sir, that I wasted the many hours __________ I should have studied in class.

I am ashamed, sir, that I wasted the many hours __________ I should have studied in class.

1. A.
   while
2. B.
   before
3. C.
   which
4. D.
   when

I am ashamed, sir, that I wasted the many hours _____ I should have studied in class.

       A. while              B. as                  C. once                     D. when

I am ashamed, sir, that I wasted the many hours __________ I should have studied in class.

A. while                       B. before                        C. which                      D. when

I am ashamed, sir, that I wasted the many hours __________ I should have studied in class.