I regret _____ hard at school, or I would have succeeded in passing the exam.
| A．not to work | B．having not worked |
| C．to have not worked | D．not having worked |
People who cannot _____ between colours are said to be colour-blind.
| A．distinguish | B．compare | C．contrast | D．distribute |
When we went past her house, we heard her ____ in her room.
| A．dance | B．dancing | C．sing | D．singing |
To get there in time, they came ______ all the way.
| A．to run | B．running | C．ran | D．run |
Finding her car stolen, ___________.
| A．a policeman was asked to help |
| B．the parking place was searching thoroughly |
| C．it was looked for everywhere |
| D．she hurried to a policeman for help |
In doing scientific experiments one must be _______ careful with the instruments.
| A．other than | B．rather than | C．less than | D．more than |