用作前缀(pref.)

B comes before C in the alphabet.B在字母表里排在C之前。

He made a statement before the House of Commons.他在下议院当众发表了一个声明。

He always put the interests of others before his own.他总把他人的利益放在第一位。

用作副词(adv.)

I'd met him once before.我曾经见过他。

I have seen that film before.那部电影我以前看过。

I was inspired to work harder than ever before.我受激励比以往任何时候都更加努力地工作。

He used to get some shut-eye before the game.他以往常常在比赛前睡一会儿。

He overlooked the contract before he signed it.他在签字之前仔细阅读了合同。

I'll try to rush the book through before Saturday.我会设法在星期六之前把这本书赶紧看完。

用作介词(prep.)

The man standing before the blackboard is our Engpsh teacher.
站在黑板前面的那个人是我们的英语老师。

We got up before sunrise.
我们在太阳升起之前起床。

Before crossing the road, you should have a look at both ways.
过马路之前,你应该看看路的两边。

Quapty comes before quantity.
品质优于数量。

We must stop and rest before going any farther.
我们必须停下来休息一下再向前去。

You must pay attention to this problem before every thing.
你应该首先注意这个问题。

The criminal case comes before the court.
那桩刑事案件已送法院审理。

Great sums of money were placed before the scientists by the government.
政府为科学家们提供了大笔的经费。

What do you earn before tax?
在未缴税前你的收入是多少?

He would die before betraying his country.
他宁愿一死,也不肯叛国。

用作连词(conj.)

Be a pupil before you become a teacher.
先做学生,再做老师。

He will come to see you before he leaves Beijing.
他离开北京之前会来看你的。

It will be some time before we know the full results.
还要过一些时间我们才能知道全部结果。

It will be eight years before we meet.
八年以后我们才能相见。

His father died before he was born.
他父亲在他出世以前就去世了。

He had left for the United States just before the letter arrived.
他恰好在信到之前去美国了。

She died before she reached the hospital.
她还没有到医院就死了。

I had barely come in before the telephone rang.
我刚进来,电话就响了。

Barely had she sat down before the play began.
她刚坐下,戏就开始了。

We had scarcely left the house,before it began to rain.
我们刚刚离家，天就下起雨来。

I will die before I'd surrender.
我宁愿死也不投降。

He'd sit alone in the dark before he'd watch TV.
他宁愿一个人在黑暗里坐着也不看电视。

We must stop and rest before going any farther.
我们必须停下来休息一下再向前走。

用作副词(adv.)

We saw that film before.
那部电影我们以前看过。

I (have) read the book before.
我以前读过这本书。

It came across my mind that I had met him somewhere before.
我突然意识到我曾在什么地方见过他。

用作介词 (prep.)动词+～

appear before在(某时)之前出现;出庭

carry before迅速获胜,势如破竹

come before在…之上,比…重要;被交由…处理；被提交…考虑

complain before控诉

go before出现在某人面前；送于…讨论；先于；早于

lay before提出

set before把…放在…前面；认为…比…更重要；把…提交…考虑

stand before站立在…前面，来到…面前，面对，面临，抵御，抵挡

carry the world before one一举大获成功

cast pearls before swine对牛弹琴,明珠暗投

put the cart before the horse本末倒置,倒行逆施

sweep all before one获得彻底的胜利，所向无敌

be brought before the bench被带到法庭受审

take sb before court将…送上法庭

～+名词

before day破晓前

before long不久,很快;在短时间内

before one's eyes当着某人的面

before one's time在时代前面;思想过于先进

before the mast充当水手

before time提前

before the wind顺风

before the world在众人面前，公然

the day before yesterday前天

the week before last上上星期

～+副词

before now从前,以前

prep.(介词)

before可用于表示时间。首先，可以表示“先于，在…以前”，其后可以跟表示具体日期、时间等的名词或数词，也可以跟表示时间或动作的名词。其次，可以表示“在做…之前”，后接 v -ing。再次，可以表示“紧接在…之前”。before用于否定句还可表示“直到…为止”。注意before之后只能接表示时间点的名词，而不能接表示时间段的名词。

before可用于表示动态或静态的位置，意思是“在…之前”，与behind相对。

before可用于表示顺序或排列上的“在…之前”或“居于…之前”，与after相对。引申可用于表示比较，即在等级、价值、重要性、能力等方面的“在先”“优于”“重于”。再引申则可用于表示对某事物的优先选择，即“宁可”或“与其…宁可”。

before还可表示“面对，在…眼前，在…面前”“有待于去完成”“在审理中，由…考虑”“在…压力下”等。

conj.(连词)

before主要引导时间状语从句，意为“先于”“…之后才”“(不多久)就…”。当主句是将来时时，从句谓语动词须用现在时；当主句是一般过去时或过去完成时时，从句常用过去时。before引导的时间状语从句不能用于否定式。

before还可用于barely〔scarcely〕...before结构，意为“刚…就…”。

before还可引导让步状语从句，意思是“宁愿…也不…”。

before引导的从句常用省略句型。

adv.(副词)

before用作副词时,意思是“以前,在前面”,表示从较近的过去至较远的过去。用作时间状语泛指以前、不与具体时间连用时，谓语动词可以用一般过去时,也可用现在完成时,前者只表示“过去发生过”,后者则强调“对现在有影响”。

before与具体时间连用时,一般置于其后，谓语动词通常用过去完成时。

before也可表示空间或位置的“在前，在前面”，还可表示运动“到前面”。

Before同ago的比较：表示“早于现在多少时间前”，用ago。表示“早于过去某时多少时间前”，通常用before 。表示“早于将来某时多少时间前”，也用before。表示“早于任何某时（不是现在、过去或将来的某时）多少时间前”，仍用before。表示“从现在说到以前，不特指若干时间”时，用before。在倒数回以前，表示“一些事情已发生了多久”时，可用before。

He started five minutes ago.

He told me he had seen her a few minutes before.
英美人也有用ago，觉得语气比较生动。

When you call at the shop again this afternoon, you may be told that the book has been sold only a few minutes before.

He often forgets what he has heard only a few minutes before.

We (have) met them many times before.

When I went back to the town that I had left eight years before, everything was different.

before与不同介词搭配时，句子意思有差异。

All day, as three days before, we planted trees.
同三天前一样，我们一整天都在种树。

All day, as for three days before, we planted trees.
同以前的三天一样，我们一整天都在种树。

before既可作副词，也可作介词，如在three hours before中为副词。在before three o'clock中为介词，但要注意before不能在表示“一段时间”的词前作介词，不能说before a month，可说a month ago；

before long，属于习语，表示“不久以后”，同before a long time has passed意思一样。before very long也指“不久以后”，但比before long时间短；

要注意before的表达方式，不能说before five minutes of the accident，而是five minutes before the accident。其他表达方式如下：

A few minutes before the accident she called on me.
（不含the/for）

During the few minutes before the accident she had a chat with me.
（含the）

For a few minutes before the accident she had a chat with me.
（含for）

before作连接词，指“……以前”时，后接到从句中的动词一般不能用将来时。如不可以说He will arrive before she will start，可以说He will arrive before she starts。若是表示“长久以后才会发生的事”时，可用将来时。

It will not be long before they come back.
他们很快就回来了。

conj.(连词)铃还没响，同学们就走出去了。

误 The students went out before the bell didn't ring.

正 The students went out before the bell rang.

before引导的时间状语从句不能用于否定句。

before的相关资料：

用作前缀(pref.)

B comes before C in the alphabet.B在字母表里排在C之前。

He made a statement before the House of Commons.他在下议院当众发表了一个声明。

He always put the interests of others before his own.他总把他人的利益放在第一位。

用作副词(adv.)

I'd met him once before.我曾经见过他。

I have seen that film before.那部电影我以前看过。

I was inspired to work harder than ever before.我受激励比以往任何时候都更加努力地工作。

He used to get some shut-eye before the game.他以往常常在比赛前睡一会儿。

He overlooked the contract before he signed it.他在签字之前仔细阅读了合同。

I'll try to rush the book through before Saturday.我会设法在星期六之前把这本书赶紧看完。

用作介词(prep.)

The man standing before the blackboard is our Engpsh teacher.
站在黑板前面的那个人是我们的英语老师。

We got up before sunrise.
我们在太阳升起之前起床。

Before crossing the road, you should have a look at both ways.
过马路之前,你应该看看路的两边。

Quapty comes before quantity.
品质优于数量。

We must stop and rest before going any farther.
我们必须停下来休息一下再向前去。

You must pay attention to this problem before every thing.
你应该首先注意这个问题。

The criminal case comes before the court.
那桩刑事案件已送法院审理。

Great sums of money were placed before the scientists by the government.
政府为科学家们提供了大笔的经费。

What do you earn before tax?
在未缴税前你的收入是多少?

He would die before betraying his country.
他宁愿一死,也不肯叛国。

用作连词(conj.)

Be a pupil before you become a teacher.
先做学生,再做老师。

He will come to see you before he leaves Beijing.
他离开北京之前会来看你的。

It will be some time before we know the full results.
还要过一些时间我们才能知道全部结果。

It will be eight years before we meet.
八年以后我们才能相见。

His father died before he was born.
他父亲在他出世以前就去世了。

He had left for the United States just before the letter arrived.
他恰好在信到之前去美国了。

She died before she reached the hospital.
她还没有到医院就死了。

I had barely come in before the telephone rang.
我刚进来,电话就响了。

Barely had she sat down before the play began.
她刚坐下,戏就开始了。

We had scarcely left the house,before it began to rain.
我们刚刚离家，天就下起雨来。

I will die before I'd surrender.
我宁愿死也不投降。

He'd sit alone in the dark before he'd watch TV.
他宁愿一个人在黑暗里坐着也不看电视。

We must stop and rest before going any farther.
我们必须停下来休息一下再向前走。

用作副词(adv.)

We saw that film before.
那部电影我们以前看过。

I (have) read the book before.
我以前读过这本书。

It came across my mind that I had met him somewhere before.
我突然意识到我曾在什么地方见过他。

用作介词 (prep.)动词+～

appear before在(某时)之前出现;出庭

carry before迅速获胜,势如破竹

come before在…之上,比…重要;被交由…处理；被提交…考虑

complain before控诉

go before出现在某人面前；送于…讨论；先于；早于

lay before提出

set before把…放在…前面；认为…比…更重要；把…提交…考虑

stand before站立在…前面，来到…面前，面对，面临，抵御，抵挡

carry the world before one一举大获成功

cast pearls before swine对牛弹琴,明珠暗投

put the cart before the horse本末倒置,倒行逆施

sweep all before one获得彻底的胜利，所向无敌

be brought before the bench被带到法庭受审

take sb before court将…送上法庭

～+名词

before day破晓前

before long不久,很快;在短时间内

before one's eyes当着某人的面

before one's time在时代前面;思想过于先进

before the mast充当水手

before time提前

before the wind顺风

before the world在众人面前，公然

the day before yesterday前天

the week before last上上星期

～+副词

before now从前,以前

【近义词】

adv.
• ago
• ahead

【反义词】

prep.
• after
• behind
adv.
• after