Mr. Irvine, who ________ in a high school for forty years, is now living in retirement.

A. had taught       B. taught       C. has taught           D. had been teaching

Mr. Irvine, who ______ in a high school for forty years, is now living in retirement.

1. A.
   had taught
2. B.
   taught
3. C.
   has taught
4. D.
   had been teaching

Mr. Irvine, who ________ in a high school for forty years, is now living in retirement.