12. Mr Black has two sons, ________ are fond of collecting stamps.
| A．all of whom | B．all of them | C．both of them | D．both of whom |
Some passers-by witnessed the car accident ______ five passengers were killed.
| A．where | B．which | C．that | D．when |
I tried all I could_____ the topic at the meeting, but he brought it up.
| A．avoided mentioning | B．to avoid mentioning |
| C．avoiding to mention | D．avoiding mentioning |
----The singer together with her band_______ invited to the concert. Did you enjoy that party?
----No, hardly_____ when they sang their top hit Oh, My Baby.
| A．was, I had left | B．were, I have gone |
| C．was, had I left | D．were, did I leave |
Many people can’t learn lessons from the mistakes they’ve made_____they get hurt somehow.
| A．whether | B．unless | C．if | D．as |
We shall not start the project until it_____ by the committee.
| A．will be approved | B．has been approved |
| C．approves | D．is to approve |