leave的過去式、過去分詞和現在分詞

例句：

1、 It's a long time since they left.

他們已經離開很久了。

2、 When I left they were all still hard at it.

我離開的時候他們都還在努力工作。

3、 Many people leave the land to find work in towns and cities.

許多人離開農村到城鎮裏找工作。

4、I'm still due 15 day's leave.

我還應有15天的休假。

5、 It's not for me to say why he left.

不適宜由我説出他離開的原因。