? ? ? ? 1.Half an hour had gone by, but the last bus hadn't come yet. We had to walk home.

? ? ? ? 2.Mary looks worried about the Chinese exam, because she hadn't learnt the text by heart.?

? ? ? ? 3.Since the basketball match has been postponed, we may as well visit the museum.

? ? ? ? 4.He lived with his parents in Australia all the way through the Second World War.

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