We can never forget the days _______ the two astronauts in spaceship worked together and the days ________ we spent together.

 A. when; which  B. which; when  C. what; that    D. on which; when

We can never forget the days _______ the two astronauts in spaceship worked together and the days ________ we spent together.

 A. when; which  B. which; when  C. what; that  D. on which; when

5. We can never forget the days _______ the two astronauts in spaceship worked together and the days ________ we spent together.

 A. when; which  B. which; when  C. what; that  D. on which; when

We can never forget the days _______ the two astronauts in spaceship worked together and the days ________ we spent together.

 A. when; which  B. which; when  C. what; that  D. on which; when

We can never forget the days _______the two astronauts in spaceship worked together and the days _______we spent together.

A. which; when          B. when; which      C. what; that         D. on which; when