Mr Brown is a（n）__________ secretary in our office, for he is able to do tasks successfully, without wasting time and energy.
| A．effective | B．efficient |
| C．flexible | D．sufficient |
He loves breathing fresh air in the suburbs and ______ in the morning sunshine.
| A．sit |
| B．sitting |
| C．sits |
| D．is sitting |
Though the man was badly hurt in the accident, he was still ______ and could think clearly.
| A．awake |
| B．aware |
| C．conscious |
| D．confused |
- Could you do me a favor?
- It depends on ______ it is.
| A．which |
| B．whichever |
| C．what |
| D．whatever |
Over the past decades, the sea ice ______ in the Arctic as a result of global warming.
| A．had decreased |
| B．decreased |
| C．has been decreasing |
| D．is decreasing |
Giving up smoking______the risk of heart disease.
| A．reduces |
| B．collect |
| C．increase |
| D．warn |