How can you expect him to make any progress ____ you never give him a chance to have a try?
| A．when | B．unless | C．even though | D．until |
With drink and food __________，the prisoner had to walk out of the cave where he was hiding.
| A．running out |
| B．using up |
| C．to use up |
| D．run out |
These new measures will put many small businesses at __________ risk, so he must look for __________ way out.
| A．the; the |
| B．the; a |
| C．a; the |
| D．不填；a |
Once upon a time, a （n）__________ famous scientist said that life was not easy for any of us but first of all we should believe in ourselves.
| A．another |
| B．sure |
| C．some |
| D．certain |
He let me repeat his instructions __________ sure that I understood what was __________ after he went away.
| A．to make; to be done |
| B．making; doing |
| C．to make; to do |
| D．making; to do |
David couldn't tell __________ from far away whether the green traffic light meant going straight or turning left.
| A．on purpose |
| B．at random |
| C．in short |
| D．for sure |