第二部分：英语知识应用
第一节：单项选择（共15小题；每小题1分，满分15分）
21. _____ is known to us all is that the 2010 World Expo will take place in Shanghai.
A. It B. What C. As D. Which
22. Only when you ____ what you have learned to practice _____ say you have made it.
A. adapt; you can B. apply; can you C. use; you can D. adopt; can you
