①第一句:半个小时过去了，但是末班车还没来。是一个并列句（表转折）。时态要注意，事情的发生有先后顺序，第一句用过去的过去即过去完成时，第二句用过去式。“只好”表示一种迫不得已:have no choice but to do
After half an hour had gone by, the last bus hadn't come. We had no choice but to go home on foot.
②句子表示因果关系，主干为: Marry 看上去很担心考试，因为她没背课文。“看上去”用: seem to be。
Marry seems to be worried about the Chinese exam because she has not learnt the text by heart.
③主干为:篮球赛被推迟，我们去参观图书馆。“既然”用 since ,“不妨”用might as well（后加动词原形），第一句推迟语态用被动语态。
Since the basketball match have been postponed, we might as well visit the museum.
④主干:他住在澳大利亚，和父母表示伴随状语，整个二次世界大战期间表示时间状语。
He lived in Australia with his parents all the way during the World War Ⅱ.
⑤主干为:我与大学同学失去了联系，“自……至今”用since，kind of 这替代的是可以说。时态用现在完成时，graduate 因为主语和主句主语一致是我，所以要用graduating。
Since graduating from NanJing University in 1985, I have kind of lost touch with my classmates.
