We can go in my car ______ you want to walk.
| A．if | B．because |
| C．unless | D．when |
—Did you notice a boy in blue come in?
—No , I didn't because I ______ a movie.
| A．had watched | B．have watched |
| C．was watching | D．am watching |
—Do you like playing computer games?
—No, but I ______ .
| A．didn't use to | B．wasn't used to |
| C．was used | D．used to |
Don't let yesterday ______ too much of today.
| A．put up | B．use up |
| C．look up | D．get up |
Most people have realized the ______ of protecting the environment.
| A．success | B．importance |
| C．experience | D．experiment |