All Mrs Smith's efforts to tidy the room were _____ because her grandson soon made a mess of it again.
| A．at all costs | B．at random |
| C．in vain | D．in return |
The WHO thinks highly of the measures all the departments in China __________ to prevent large-scale outbreak of the disease.
| A．make | B．settle |
| C．organize | D．take |
__________ twice a year is the rule that every driver shall obey in this city.
| A．Being examined | B．Examined |
| C．To examine | D．Having examined |
Playing on the football pitch __________.
| A．some students are with their P. E. teacher |
| B．their P. E. teacher is with some students |
| C．some students with their P. E. teacher are |
| D．are some students with their P. E. teacher |
With the development of the Internet, e-mail has largely __________ the traditional business letter.
| A．exchanged | B．reduced |
| C．replaced | D．traded |
I won't buy this iPhone unless the price __________ to under 2，000 yuan.
| A．reduces | B．will be reduced |
| C．has reduced | D．is reduced |