(1) Half an hour went by, but the last bus hasn't come. We had to walk home.
由“过去了”知句子时态:一般过去时；这两个句子为并列句。
(2) Mary seems to be worried about the Chinese exam because she hasn't learnt the text by heart.
时态:现在完成时；主干:玛丽对考试担心；句间关系为因果关系。
(3) Since the basketball match has been postponed, we may as well visit the museum.
由“已被推迟”知句子时态:现在完成时的被动语态。
(4) During the World War ll, he lived in Australia with his parents all the way.
由“二次世界大战”知句子时态:一般过去时；主干:他和父母住在澳大利亚。
(5) Since I graduated from Nanjing University in1985, I have kind of lost touch with my college classmates.
由“自1985年……至今”知句子时态:现在完成时；主干:我与大学同学失去了联系。
