ago和before的区别和用法
ago和before两者均可表示在多久时间“以前”(要放在表示一段时间的词语之后)，但有区别：ago从现在向前回溯，即现在的过去，因此通常与一般过去时连用；而before则从过去向前回溯，即指过去的过去，因此通常与过去完成时连用。
ago的用法
(1)The last time I saw her was about sixteen years ago.
我上次见她大约是16年前了。
(2)A few years ago Bacryl took charge of the company.
几年前，巴克里尔接管了该公司。
(3)They talked about their life in Beijing twenty years ago.
他们谈到了20年前在北京的生活。
(4)I met George well over a year ago.
我认识乔治已经是一年多前的事了。
(5)He should have come home long ago.
论理上他早该回家了。
(6)I qualified as a doctor from London University over 30 years ago.
30多年前，我从伦敦大学毕业，取得了行医资格。
before的用法
(1)Everyone in the room knew it was the single hardest task before them.
房间里所有人都清楚，摆在他们面前的是最为艰巨的任务。
(2)Her husband, her children,and the Church came before her needs.
丈夫、孩子和教会都比她本人的需求重要。
(3)Before World War II,women were not recruited as intelligence officers.
在第二次世界大战之前，女性不能当情报人员。
(4)My husband rarely comes to bed before 2 or 3am.
我丈夫很少在凌晨两三点之前睡觉。
(5)Before leaving,he went into his office to fill in the daily time sheet.
离开前，他到自己的办公室填写了日常考勤表。
(6)I had met Professor Lown before.
我以前见过劳恩教授。
