1.Half an hour had gone by, but the last bus had not come.So we had to walk home.

2.Mary seemed to be worried about the Chinese exam because she has not learned the passage by heart.

3.Since the basketball competition has been postponed, we might as well visit the museum.

4.He stayed in Australia with his parents all the way through the World War Ⅱ. 

5.Since I graduated from Nanjing University in 1985, I have kind of  lost touch with my classmates.