—Would you mind giving your advice on how to improve our efficiency?
—If you make _____ most of forty-five minutes classes day after day, there will be _____ switch in grades.
| A．/; / | B．the; a | C．/; a | D．the; / |
The factory has been ________ for two years.
| A．open | B．to open | C．opening | D．opened |
Paris is ______ most beautiful city, where you can see ______ famous Eiffel Tower.
| A．a, the | B．a, / | C．the , an | D．/,the |
--Where' s Mr Green? --Oh, he _________ Canada.
| A．has been to | B．has gone to | C．went to | D．was in |
Beyond _______ stars, the astronaut saw nothing but ________ space.
| A．the ,/ | B．/, the | C．/,/ | D．the ,the |
The headmaster ________for more than two weeks.
| A．has left | B．has gone | C．has been away | D．has come back |