If you suffer an injury during ______ exercise, or if _______ pain or discomfort makes you think an injury is developing, stop right away and call me.

A. the; a                     B. 不填; the             C. an; the                  D. 不填; 不填

If you suffer an injury during ______ exercise, or if _______ pain or discomfort makes you think an injury is developing, stop right away and call me.

1. A.
   the; a
2. B.
   不填; the
3. C.
   an; the
4. D.
   不填; 不填

If you suffer an injury during ______ exercise, or if _______ pain or discomfort makes you think an injury is developing, stop right away and call me.

A. the; a                     B. 不填; the             C. an; the                  D. 不填; 不填

If you suffer an injury during ______ exercise, or if _______ pain or discomfort makes you think an injury is developing, stop right away and call me.