—Can I borrow your car?
—Well..., _______.
| A．if you must | B．if you need |
| C．if you can | D．if you should |
Tony was very unhappy for _______ to the party.
| A．having not been invited | B．not having invited |
| C．having not invited | D．not having been invited |
The research is so designed that once _______ nothing can be done to change it.
| A．begins | B．having begun |
| C．beginning | D．begun |
After graduation she reached a point in her career __________ she had to decide what to do.
| A．that | B．what |
| C．which | D．where |
Edward, you play so well. But I ________ you played the piano.
| A．didn’t know | B．hadn’t known |
| C．don’t know | D．haven’t known |
Not until I began to work ________ how much time I had wasted.
| A．didn’t I realize | B．did I realize |
| C．I didn’t realize | D．I realize |