After ________ series of unsuccessful attempts, he has finally passed ________ driving test.
| A．/; the | B．a; the | C．the; a | D．/; a |
In science fiction we read of flying saucers travel through _____ space, so people want to have ______ better knowledge of the universe. 
| A．the; a | B．/; / | C．the; / | D．/; a |
In order to find _______ better job, he decided to study _________ second foreign language.
| A．the; a | B．a; a | C．the; the | D．a; the |
The biggest whale is ___ blue whale, which grows to be about 29 meters long—the height of ___ 9-story building.
| A．the; the | B．a; a | C．a; the | D．the; a |
We can never expect____bluer sky unless we create____less polluted world.
| A．a; a | B．a; the |
| C．the; a | D．the; the |
Some people fear that ________ air pollution may bring about changes in _______ weather around the world.
| A．/; the | B．the; / | C．an; the | D．the; a |