We work together to achieve our common purpose： ______ world that is safer, cleaner and healthier than______ one we found．
| A．the；the | B．a；不填 | C．a；the | D．the；不填 |
—I__________some photos to be developed (冲洗). Are they ready yet?
—Yes. Here you are.
| A．left | B．will leave | C．have left | D．had left |
Once again he failed to hand in his homework _____ he had been given enough time to do it.
| A．in case | B．as though | C．so that | D．even though |
. _____ the book four times, I finally understood the author's theory.
| A．Reading | B．Having read | C．To read | D．Read |
Mike seldom asks ____ questions in class, but today he raised _____ fairly good one.
| A．/; a | B．the; a | C．/; the | D．/; / |
_____ the news, so far, has been good, there may be days ahead when it is bad.
| A．While | B．When | C．As | D．Since |