A giant helium（氦） balloon is telling residents of Paris how good or bad the air quality is．When it’s good, the balloon ----measuring 22 meters wide and 32 meters high---shines green．_________, it’s red．
| A．Though terrible | B．Whenever good |
| C．If worse | D．When bad |
Isn't it time you got down to __________ the papers?
| A．mark | B．be marked |
| C．being marked | D．marking |
In some parts of London, missing a bus means __________ for another hour.
| A．waiting | B．to wait |
| C．wait | D．to be waiting |
You can't imagine what great trouble they have __________ the problem __________.
| A．to solve; being talked about | B．solving; discussing |
| C．to solve; to talk about | D．solving; being discussed |
The boy was criticized for forgetting __________ his textbooks to school.
| A．bringing | B．to bring |
| C．having brought | D．to have brought |
Practice __________ English every day, and you will surely improve your spoken English.
| A．speaking | B．to speak |
| C．having spoken | D．to be spoken |