____ it rain tomorrow, I’d stay at home.
| A．Should | B．Would | C．When | D．If |
— Is Mr Smith rich? 
— Yes, very rich. When he worked in ________town, he earned a lot. Now he has a big farm in ________ country.
| A．at; the | B．/; / | C．/; the | D．the; / |
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 |