We should prevent such a silly mistake _____ again.
| A．occurring | B．to occur | C．to be occurred | D．from being occurred |
The police were seeking more information to find out________ killed the rich merchant.
| A．who it was that |
| B．who was it that |
| C．it was who |
| D．who was it |
Had they known what was coming next, they _________second thoughts.
| A．may have | B．could have |
| C．must have had | D．might have had |
Studying Tom’s menu, I found that many of the items are similar to ________ of McDonald’s.
| A．those | B．ones |
| C．any | D．all |
People who do not smoke have less ______of suffering from lung cancer than those who do so.
| A．potential | B．pattern |
| C．preference | D．prejudice |
This factory produced much dirty water, which resulted in a wide _______ of environmental problems.
| A．branch | B．range |
| C．species | D．wave |