A. | when | B. | which | C. | where | D. | that |
A. | that | B. | what | C. | which | D. | whether |
A. | when | B. | where | C. | what | D. | which |
A. | mustn't | B. | couldn't | C. | needn't | D. | wouldn't |
A. | haven't seen | B. | hadn't seen | C. | didn't see | D. | don't see |
A. | didn't know | B. | I don't know | C. | wasn't knowing | D. | hadn't known |