Scientists have to work hard to keep _____ with modern discoveries and developments.
| A．company | B．track | C．touch | D．pace |
If I ____________out of my ink, I would have finished writing the paper.
| A．didn’t run | B．shouldn’t run | C．haven’t run | D．hadn’t run |
The professor gave orders that the test ___________before 5:30.
| A．be finished | B．will finish | C．will be finished | D．shall be finished |
The possibility of a way out of the impasse(僵局) had never ____________ to anyone.
| A．happened | B．occurred | C．appeared | D．flashed |
I appreciated ____ the opportunity to study abroad two years ago.
| A．having been given | B．having given | C．to have been given | D．to have given |
_______, I’d have told you.
| A． If I would have known | B． If I had have known |
| C． Had I known | D． Should I know |