5. When _____ different cultures, we often pay attention only to the differences without noticing
the many similarities.（2006-浙江）
A. compared B. being compared
C. comparing D. having compared
6. Sugar, when ___ with water, dissolves quickly.（2005年-上海春）
A. mixed B. mixing
C. mix D. is mixed
7. When help, one often says “Thank you.” or “It’s kind of you.”（2005-福建）
A. offering B. to offer
C. to be offered D. offered
8. When first _____ to the market, these products enjoyed great success.（2004-全国Ⅱ）
A. introducing B. introduced
C. introduce D. being introduced
9. It shames me to say it, but I told a lie when ______ at the meeting by my boss（2004-全国Ⅳ）
A. questioning B. having questioned
C. questioned D. to be questioned
10. _______ with the size of the whole earth, the biggest ocean does not seem big at all.（2004-
湖北）
A. Compare B. When comparing
C. Comparing D. When compared
11. Generally speaking, ____ according to the directions, the drug has no side effect. [2003-上海]
A. when talking B. when taken
C. when to take D. when to be taken
12. Unless ______ to speak, you should remain silent at the conference. [2003-上海春]
A. invited B. inviting
C. being invited D. having invited
13. The research is so designed that once _____, nothing can be done to change it. [2002-全国]
A. begins B. having begun
C. beginning D. begun
14. Though ______ money, his parents managed to send him to university. [2002-上海]
A. lacked B. lacking of
C. lacking D. lacked in
15. When ______, the museum will be open to the public next year. [2002-上海春]
A. completed B. completing
C. being completed D. to be completed
16. Some of you may have finished Unit One. _____, you can go on to Unit Two. [2009-江西]
A. If you may B. If you do
C. If not D. If so
17. While building a tunnel through the mountain, ______. [2000-上海春]
A. an underground lake was discovered B. there was an underground lake discovered
C. an underground lake was discovered D. the workers discovered an underground lake