. — Why does the Lake smell terrible?
—Because large quantities of water______.
| A．has polluted | B．have been polluted |
| C．has been polluted | D．is being polluted |
With a lot of difficult problems _______, the newly-elected president is having a hard time.
| A．settled |
| B．settling |
| C．to settle |
| D．being settled |
It was unbelievable that the fans waited outside the gym for three hours just ____ a look at the sports stars.
| A．had |
| B．having |
| C．to have |
| D．have |
____ into use in April 2000, the hotline was meant for residents reporting water and heating supply breakdowns.
| A．Put |
| B．Putting |
| C．Having put |
| D．Being put |
_____ to sunlight for too much time will do harm to one's skin.
| A．Exposed |
| B．Having exposed |
| C．Being exposed |
| D．After being exposed |
He got well-prepared for the job interview, for he couldn’t risk ____ the good opportunity.
| A．to lose |
| B．losing |
| C．to be lost |
| D．being lost |