—Such a mistake could have been avoided.
—Unfortunately, he_______the mistake again and again
| A．repeated | B．would repeat | C．has been repeated | D．would have repeated |
--------- ___________did they visit the moon last month?
---------They visited it in a spaceship
| A．When | B．Where | C．What | D．How |
He was about to tell me the secret___________someone called him by his name.
| A．as | B．until | C．while | D．when |
He used to make a living_________playing music on festivals. Now he makes shoes__________ his own hands.
| A．by；with | B．on；by | C．with；with | D．by；by |
We can’t continue to pretend that the problem of pollution doesn’t___________in this city.
| A．exist | B．live | C．be | D．survive |
We must do whatever we can to ______the river from being polluted any more.
| A．separate | B．keep | C．prevent | D．guard |