______ until the lights have turned to green.
| A．Wait | B．To wait |
| C．Waiting | D．Having waited |
The environmental organization calls on customers not to purchase these _______ packages of food, clothes and gifts.
| A．intrusive | B．cognitive |
| C．excessive | D．sensitive |
People are advised not to smoke at home, since passive smoking is ________ topeople around them. Which is Not proper for the blank?
| A．dangerous | B．protective |
| C．hazardous | D．risky |
He stumbled(绊倒)on the _______ ground and fell flat on his face.
| A．undeniable | B．unfair | C．unavoidable | D．uneven |
Many students today suffer from ________ problems, since they are under too much pressure.
| A．recreation-related | B．pollution-related |
| C．stress-related | D．pollution-free |
________ energy is generated from natural resources—such as sunlight, wind, rain, tides and so on.
| A．Recyclable | B．Non-renewable |
| C．Rechargeable | D．Renewable |