Not until ________a third time ________that he had given birth to the reading system for the blind called Braille.
| A．Louis Braille tried; he announced |
| B．did Louis Braille try; he announced |
| C．Louis Braille had tried; did he announce |
| D．had Louis Braille tried; had he announced |
_____ of the students who took part in the military training is 750.
| A．A number | B．A lot | C．Dozens | D．The number |
What way are you thinking of _____ rid of the flies?
| A．to get | B．getting | C．being got | D．to be getting |
It is difficult to imagine his _____ the decision without any consideration.
| A．accept | B．accepting | C．to accept | D．accepted |
When the space ship was ____, I could really feel the high gravity.
| A．lifting off | B．landing | C．sending away | D．giving a lift |
--- Did you hear someone talking in the living room?
--- Oh, I forgot to ____ the TV just now.
| A．switch off | B．switch on | C．turn on | D．switch over |