一.before long 意为“不久(之后)，立刻，马上，很快就”(=soon, in a short time， a little later),long为名词。“before long”常与一般将来时或一般过去时连用。与一般将来时连用时，描述将来很快会发生的动作；与一般过去时连用时，指过去某个时间之后不久发生的动作。
例如：He said he would arrive before long.（他说他不久就会到达。）
例：
1. We shall finish before long. 我们很快就会千完。
2.Before long she came running behind me. 很快,她就跑着追我了。
3.Before long we got to the station. 很快我们就到了车站。
4. The petrol had nearly all been used up. Before long , the noise dropped completely and the boat began to drift gently across the water.( New Concept English, Book 2,L. 86)
汽油已差不多用完了,不一会儿马达声完全消失,汽艇开始缓慢地漂在水面上。
5. Before long, I leaned over and put my head on her shoulder. It was our first date. ( B. Clinton，My Life)
不久,我就俯下身去,把我的头放在了她的肩膀上。这是我们的第一次约会。《我的生活》
6. “| have enjoyed my visit very much. "
“We hope to see you again before very long."
“我非常喜欢这次访问。”
“我们希望不久后能再见到你。”
7.We'll know before long.
我们很快就会知道了。
8.We'll be home before long.
我们很快就要到家了。
9.Before long he took over the editing of the magazine.
他不久就接手负责杂志的编辑工作。
10.German interest rates will come down before long
德国的利率水平很快就会降下来。
11.Before long, we were deep in conversation.
没过多久，我们便聊得很起劲了。
12.Before long we all grew bored with his frequent recital of the foods he couldn't eat
他总是唠叨自己不能吃的那些食物，不久我们所有人都听烦了。
13. Before long, he will come back.
不久以后，他就会回来。
14. Before long, she was promoted to manager.
不久后，她就晋升为经理了。
15. Before long, the whole town knew about the scandal.
很快，全镇人都知道了这件丑闻。
16. After their first date, they fell in love before long and got engaged within six months.
第一次约会后，他们很快坠入爱河，并在六个月内订了婚。
17. After resolving their differences, the couple reconciled before long and rebuilt their happy family.
解决分歧后，这对夫妻很快和好如初，重新构建起幸福的家庭。
18. Before long, they will start a new life together.
不久后，他们将开启共同的新生活。
19. Joining the book club, she made a circle of like - minded friends before long.
加入读书俱乐部后，她很快就结交了一群志同道合的朋友。
二.long before意为“很久以前”,“早在…之前”。（a long time earlier）
“long before”可以单独使用，也可以后接名词、代词或从句。例如：
I had seen the film long before.
我很久以前就看过这部电影。也可以说：
Long before I came here, I had heard about this place.
在我来这里很久以前，我就听说过这个地方。请看更多例句：
1. I had known her long before.
很久以前我就认识她。
2. I knew Smith long before I knew you.
早在认识你之前我就认识史密斯了。
3. She died long before the war.
早在战前很久她就去世了。
4. They began the experiment yesterday, but they had made preparations long before.
他们昨天开始做实验,但早在这之前就已经作准备了。
5. In 1951. long before molecular biologists could confirm her theory geneticist Barbara McClintock claimed that genetic information shifted from one chromosome to another.
1951年。早在分子生物学家能够证实她的理论之前，遗传学家芭芭拉·麦克林托克就声称遗传信息会从一条染色体转移到另一条染色体。
Preserved in rock, the bones of dinosaurs and the tracks made by these animals occur in many parts of the world and undoubtedly attracted attention long before they were understood.
恐龙的骨骼和这些动物留下的足迹保存在岩石中，出现在世界许多地方，毫无疑问，在人们了解它们之前很久就引起了人们的注意。
6. Long before her death in 1886, the poet Emily Dickinson had become a legend in her hometown of Amherst Massachusetts.
早在1886年去世之前，诗人艾米莉·狄金森就在她的家乡马萨诸塞州阿默斯特成为了传奇。
7. The area was inhabited long before the dawn of recorded history.
早在有历史记载之前很久这个地区就有人居住了。
8. He retired long before the war.
他在战争之前早就退休了。
9. The plot to assassinate Martin Luther King had started long before he was actually killed.
刺杀马丁·路德·金的计划在实施前酝酿已久。
10. Long before I ever went there, Africa was alive in my imagination.
早在我真正踏足之前很久，非洲就已在我的脑海中活灵活现了。
11. Shoppers began arriving long before the 10am opening time.
离上午10点开门时间还早时顾客就陆陆续续地来了。
12. There was a deep-rooted racial prejudice long before the two countries became rivals and went to war
早在这两个国家成为敌人并且兵戎相见之前，它们之间就有了根深蒂固的种族偏见。
13.She had left long before we arrived.
在我们到达很久以前，她就已经离开了。
long before”表示“很久以前”，强调过去的某个时间点或时间段。但是，这种情景也是可以用于进来时态：
14. Your baby will begin to vocalize long before she can talk.
你的女婴在会说话前很早就要开始咿呀发声了。
注意在这种否定句的用法：
15. It will not be long before the inflation figure starts to fall
过不了多久，通货膨胀率就会开始下降。
16. It was not long before the news was widely circulated.
这个消息不久就哄传开了。
17. It was not long before I realised the enormity of my faux pas.
没过多久，我就意识到自己有多么失态。
18. Long before she met her husband, she had dreamed of a fairytale wedding.
在遇见丈夫很久以前，她就憧憬着一场童话般的婚礼。
19.Long before they became roommates, they had been online friends for years.
在成为室友前，他们早已是多年的网友。
20. She realized that the friendship had ended long before they had the final argument.
她意识到，早在最后那场争吵之前，这段友谊就已经破裂很久了。
21. He had proposed to her long before she expected.
远在她意料之外时，他就已经向她求过婚了。