例句：
1、 It's a long time since they left.
他们已经离开很久了。
2、 When I left they were all still hard at it.
我离开的时候他们都还在努力工作。
3、 Many people leave the land to find work in towns and cities.
许多人离开农村到城镇里找工作。
4、I'm still due 15 day's leave.
我还应有15天的休假。
5、 It's not for me to say why he left.
不适宜由我说出他离开的原因。
