George returned after the war, only _______ that his wife had left him

The volunteers for the Shanghai World Expo are busy from dawn ______ dust but they feel very proud of it

31. All the things ______ must be done well.

Li Lei with his classmates often____ to the zoo to see animals.

It was March 3 2011 _____ a magnitude 90 earthquake struck Japan and subsequent tsunamistarted the large-scale crisis[ ]