1)半个小时过去了，时间流逝用go by表示，已过去表示已发生用had，但表示转折，用but，只好表示不得不，用had  to。

Half  an hour had gone by, but the last bus hadn’t come yet. We had to walk home.

2) 句子主干是玛丽很担心，担心内容是汉语考试，be  worried  about....,担心原因，因为用because，牢记在心，记牢用learn...by  heart.

Mary seems to be very worried about the Chinese exam because she hasn’t learned the texts by heart.

3) 既然可以用since，也可以用now that，篮球比赛，重大比赛用game，小比赛用match，已被推迟，had been  postponed,不妨去用may  as  well，这里过去，用might。

Since the basketball match has been postponed, we might as well visit the museum.

4)句子主干是他和父母住在澳大利亚，一直加all the  way，在整个第二次世界大战期间就是贯穿整个期间，用through，表示

He stayed in Australia with his parents all the way through World  WarⅡ.

5)句子主干是他与大学同学失去了联系。自...至今用since，和...失去了联系用lost  touch  with。

Since I graduated from Nanjing University in 1985, I have kind of lost touch with my  classmates

护理七班贾王玉.