______ is known to us all that Shanghai will host the 2010 World Expo.

A. Which　　　

B. This　　　　　

C. That　　　　　

D. It

.（2010·浙江温州中学高三9月月考）    13. ______ is known to us all that Shanghai will host the 2010 World Expo.

A. Which       B. As       C. That        D. It