By the time he realizes he _____ a mistake, it’ll be too late for him to change his mind.    

A. makes         B. made    C. has made     D. had made

By the time he realizes the mistake he ________，it will be too late for him to do anything about it.

    A. has made      B. made             C. makes           D. will make

By the time he realizes the mistake he ________，it will be too late for him to do anything about it.

1. A.
   has made
2. B.
   made
3. C.
   makes
4. D.
   will make

By the time he realizes he _____ a mistake, it’ll be too late for him to change his mind.

1. A.
   makes
2. B.
   made
3. C.
   has made
4. D.
   had made