Radar enables the pilot of an airliner to take off, fly and land in _____.
| A．danger | B．comfort | C．continuity | D．safety |
Seeing the soldiers well _____ for the flood-fight, the general nodded with satisfaction.
| A．prepare | B．preparing | C．prepared | D．having prepared |
Mr. Green is said _____ an experiment to prove the new method of solving the problem when young.
| A．to do | B．to have done | C．to be doing | D．to have been doing |
—— Have you considered _____ your job as a teacher?
——Yes. I like the job because a teacher is often considered _____ a gardener.
| A．to change; to be | B．to change; being | C．changing; being | D．changing; to be |
The monument was built in honor of the explorer who was believed _____ the river.
| A．to have discovered | B．to have been discovered |
| C．to discover | D．having been discovered |
The monument was built in honor of the explorer who was believed _____ the river.
| A．to have discovered | B．to have been discovered |
| C．to discover | D．having been discovered |