1.“半个小时过去了”作为时间状语。“但末班车还没来”是原因。“我们只好走回家”可以一般过去时来翻译。因此前面两句用过去完成时。
Half an hour had gone by，but the last bus hadn't come. We had to go home on foot.
2.“玛丽看上去对汉语考试很担心”为句子主干，“因为她还没有背熟课文”为原因。
Mary seems to be worried about Chinese Test because she hasn't learned text by heart.
3.句子主干为“篮球赛被推迟，我们去参观博物馆”。用到句式“既然…不妨…”
Since basketball match has been postponed，we might just as well visit a museum.
4.“他一直和父母住在澳大利亚”为句子主干，“整个二次世界大战期间”可以作为时间状语。
During the World War II he lived in Australia with his parents all the way.
5.“自1985年从南京大学毕业至今”为时间状语，“可以说我与我的大学同学失去了联系”为句子主干。“我”与“毕业”是主动关系，所以用主动语态。
Since 1985，graduate from Nanjing University, I've kind of lost touch with my classmates.
