But when I got ____ the town ought to have been, all I found was a gas
station.
| A．what | B．which | C．where | D．that |
– I wonder how much you charge for your services.
-- The first two are free ____ the third costs $30.
| A．while | B．until |
| C．when | D．before |
We can never expect____ bluer sky unless we create_____less polluted world.
| A．a; a | B．a; the |
| C．the; a | D．the; the |
She’ll never forget her stay there ________ she found her son who had gone missing two years before.
| A．that | B．which | C．where | D．when |
My uncle’s house in the downtown area is much smaller than ours , but it is twice _______ expensive .
| A．as | B．so | C．too | D．very |
—You speak very good French! 
—Thanks. I __________ French in Sichuan University for four years.
| A．studied | B．study | C．was studying | D．had studied |