---Della, would you like some potato chips?
---No potato chips for me---I’m ______ a diet.
| A．at | B．in | C．on | D．with |
ack went to college last year, _______ to return home until he achieves his goal.
| A．determined not | B．determining not |
| C．not determined | D．not determining |
_______ in the queue for half an hour, Tom suddenly realized that he had left his wallet at home.
| A．To wait | B．Having waited | C．Have waited | D．To have waited |
_______ to sunlight for too much time will do harm to one’s skin.
| A．Being exposed | B．Exposed |
| C．Having exposed | D．After being exposed |
The bell _______ the end of the period rang, _______ our heated discussion.
| A．indicated; interrupting | B．indicating; interrupting |
| C．indicating; interrupted | D．indicated; interrupted |
The research is so designed that, once _______, nothing can be done to change it.
| A．begins | B．having begun | C．begun | D．Beginning |