⑴ Half an hour had gone by, but the last bus had not come yet. We had to walk home.
半个小时已经过去，所以用过去完成时，再用but 将两个句子连接起来。yet 用在句尾增强语气，只好表示不得不，翻译成have to do sth
⑵ Mary seems to be very worried about the Chinese exam because she has not learned the texts by heart.
Mary用三人称单数seems ，看上去用seem to do sth。对...担心是be worried about sth ，并用very 修饰担心的程度。还没背熟用现在完成时态，并用because 连接两个句子。
⑶ Since the basketball match has been postponed, we might as well visit the museum.
篮球赛被推迟和我们参观博物馆是两个句子，用since 引导。已被推迟时态用现在完成时，不妨用may as well 表示，被中断是小型比赛 用match。
⑷ He stayed in Australia with his parents all the way through World WarⅡ.
时态是一般过去时，主干是他和父母住在澳大利亚。二战首字母要大写，用all the way 表示一直。
⑸ Since I graduated from Nanjing University in 1985, I have kind of lost touch with my classmates.
自从用since表示，失去联系用lose touch with。时态是一般过去时，句子主干为我和同学失去联系。
