（1）这句话可以直接翻译，半个小时过去了，为过去时。
Half an hour had gone by,but the last bus hasn't come.We have to go home on foot.
(2)这句话主干是 玛丽担心考试。原因是她没背熟课文。看上去用seem。
Mary seemed to be worried about the Chinese exam because she hasn't learnt the text by heart.
(3)既然……不妨去……是句型：now that……might as well go,可直接套用。
Now that the basketball match has been postponed, we might as well go to the museum.
(4)这句话可理解为：他一直住在澳大利亚和父母，时间是：在整个二次世界大战期间
He all the way lived in Australia with his parents throughout the Second World War.
(5)这句话可理解为：自从从南京大学毕业(时间），可以说我已经和大学同学失去了联系
Since I graduated from Nanjing University in 1985, it can be said that I have kind of lost touch with my college classmates.
