_________ environmental damage is done, it takes many years for the ecosystem to recover.
| A．Even if | B．If only | C．While | D．Once |
—I knocked over my coffee cup. It went right over ____ keyboard.
—You shouldn’t put drinks near computer.
| A．the; 不填 | B．the; a | C．a; 不填 | D．a; a |
George couldn’t remember when he first met Mr. Anderson, but he was sure it was ___ Sunday because everybody was at _____ church.
| A．/; the | B．the; / | C．a; / | D．/; a |
Of the seven days in a week, Saturday is said to be the most popular ___ for a wedding in some countries.
| A．way | B．situation | C．event | D．choice |
When Jane began to take swimming lessons, her main ____ was the fear of water．
| A．evidence | B．crisis | C．obstacle | D．danger |
I like ___ color of your skirt. It is ___ good match for your blouse.
| A．a; the | B．a; a | C．the; a | D．the; the |