He was not an actor, who often appeared on stage, _____ a writer, writing stories.
| A．but | B．and | C．then | D．so |
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 |
The teacher together with the students ________ discussing Reading Skills that ________ newly published in America.
| A．are; were | B．is; were | C．are; was | D．is; was |