27．—Why is your professor so happy recently?
—Because the theory she insisted on ________correct．
| A．is proved | B．proving | C．was proved | D．has proved |
The members of the board are discussing the problem right now; it will _____ have been solved by the end of next week．
| A．luckily | B．immediately |
| C．hopefully | D．undoubtedly |
All the citizens strongly insist those found _____ "harmful" advertisements in the street should be punished strictly．
| A．putting up | B．being put up |
| C．put up | D．to be putting up |
All the preparations for the task _____, and we’re ready to start．
| A．completed | B．complete |
| C．had been completed | D．have been completed |
A lot of people find it useful to have a phrasebook when they travel to a country _____they don’t know the language．
| A．where | B．when | C．why | D．which |
The Arabian Nights _____ well known all over the world, in which many a story_____ interesting and instructive．
| A．is; are | B．are; is | C．are; are | D．is; is |