12. _____After____ the work was done, we sat down to sum up experience总结经验.

11. He had learned Chinese ___before______ he came to China.

10. I listen to the recorder ____when_____ I have time.

9. Henry is in charge of the office __while/when______ Mr. Smith is away.

8. He learned to speak German ___when/while______ he was in Berlin.

7. We'll go to the country at the beginning of June, ____when_____ the summer harvest will start.

6. I was about to go out ____when_____ a visitor came.

5. It was already eight o'clock ___when ____ we got there.

4. Have a good look at that man ____when_____ you pass him.

3. I saw her just _____while____ she was getting off the train.