His failure made him aware ___ he had made a great mistake in working out the plan.
| A．of that | B．of | C．that | D．that of |
Can you imagine how much trouble I have __________ the work?
| A．to do |
| B．did |
| C．do |
| D．doing |
It is difficult to imagine his __________ the decision without any consideration.
| A．accept |
| B．accepting |
| C．to accept |
| D．accepted |
Students are often warned that anyone who leaves the classroom at night must remember to __________ all the lights, or he will be fined.
| A．switch off |
| B．go off |
| C．take off |
| D．bring off |
In many states of America, a neighbor may __________ you with playing your radio too loudly.
| A．charge |
| B．blame |
| C．punish |
| D．scold |
Innovation is a natural desire of the human mind to develop variety，__________ activity is involved.
| A．no matter when |
| B．however |
| C．whatever |
| D．no matter which |