<p>...前 and ...内 are the short version of 之前 and 之内 respectively.</p>

<p>They are completely interchangeable, ...前==之前， ...内==之内. 
三天前==三天之前，三天内==三天之内，第二次世界大战前==第二次世界大战之前</p>

<p>...后==之后 is the same thing. 两年后==两年之后 </p>

<p>The only difference is longer ones look more formal. </p>

CC BY-SA 3.0
2017-08-30T12:54:18.347Z
Thanks. So is the rhythm of a syllable also considered here? (e.g. if omitting 之 is better phonetically, it should be omitted, etc...)
Blaszard
CC BY-SA 3.0
2017-08-30T23:08:53.810Z
...前 is used more often than 之前, because it's concise. 之前 is a bit redundant. 之 was inherited from ancient Chinese like 其, so it's only used in certain fixed scenarios. But sometimes in a song or poem, in order to make each line aligned or for some kind of rhyme considerations, they might intentionally add 之. "十年", a Chinese song, they put “十年之前” for this kind of consideration.
dan
CC BY-SA 3.0
2017-08-31T02:07:20.653Z
If what before “前" has only one character, you usually will not use "之前". E.g., for 饭前, you usually will not say 饭之前, although I think people can understand.
fefe
CC BY-SA 3.0
2017-08-31T04:28:05.400Z
@fefe Yeah, I'd been thinking about that case too. 饭之前 is a bit odd as people rarely say it. However, 晚饭之前 or 午饭之前 sounds natural. It's tricky, huh!
dan
CC BY-SA 3.0
2017-08-30T12:34:03.630Z
2017-08-31T02:07:57.347Z
2017-08-31T02:07:57.347Z
dan
<p>之 mostly means 的
~之前 = ~的前面
~之后 = ~的后面
~之内 = ~的里面</p>

<p>if ~ is time，
~之前 = before~
~之后 = after~
~之内 = in/among~</p>

<p>美国之音 = 美国的声音 = VOA（Voice of America）</p>

CC BY-SA 3.0
2017-08-31T01:32:39.380Z
2017-08-31T01:32:39.380Z
Pengfei Fang
<p>In Mandarin, if you want to express "three years after" or "after three years", 之 should be used such that it is 两年之后. This is also true of 之前 and 之内 (e.g. 第二次世界大战之前。, 我三天之内一定做得完。).</p>

<p>However, now I wonder if it is possible to omit 之, and write it as 两年后 or 第二次世界大战前. Is this grammatically correct? Or is it wrong but nonetheless used everywhere? (I know these phrases are often used but would like to know if it is correct.)</p>

CC BY-SA 3.0
2017-08-30T12:51:09.723Z
look at examples in jukuu
user6065
CC BY-SA 3.0
2017-08-30T12:53:13.830Z
@user6065 I checked it out and got many examples. I also noted it in *"(I know these phrases are often used but would like to know if it is correct.)"*.
Blaszard
CC BY-SA 3.0
2017-08-30T13:13:21.670Z
之 can be replaced by 以 if not omitted, grammar topic(外国人实用汉语语法）：方位词组（phrase of locality)表示时间：夜里，晚上， **三天前**  ，  **饭后** ，一个星期左右，一个月以前，(no mention of 之  only 以) 之 supplies official color
user6065
CC BY-SA 3.0
2017-08-30T13:53:41.987Z
according to C. grammar 前，后，内，etc. are special types of nouns (方位词）, cf."实用现代汉语语法＂（一）。。。用于名词或名词短语后表示时间：三天前（后），十年后，三个月内，其中，本世纪中，
（二）合成方位词１。合成方位词的构成。单纯方位词前边加上＂以＂或＂之＂或者（for position）后边加上＂边＂、＂面＂、＂头＂要读轻声。不同的方位词与＂以＂、＂边＂等组合的情况不完全相同。
user6065
CC BY-SA 3.0
2017-08-31T16:21:15.963Z
@fefe Is 第二次世界战争 not a correct word? It was written as such in [my textbook](https://www.amazon.com/Modern-Mandarin-Chinese-Grammar-Practical/dp/0415827140/).
Blaszard
CC BY-SA 3.0
2017-09-01T01:14:42.053Z
As a native, this is the first time that I see WWII written in Chinese as 第二次世界战争. I even tried a search in case it may be called this somewhere, but the result is not promising.
fefe
<grammar>
Can I omit 之 in 之后/之前/之内?
# Can I omit 之 in 之后/之前/之内?

(Asked by: username_0 on 2017-08-30)

In Mandarin, if you want to express "three years after" or "after three years", 之 should be used such that it is 两年之后. This is also true of 之前 and 之内 (e.g. 第二次世界大战之前。, 我三天之内一定做得完。).

However, now I wonder if it is possible to omit 之, and write it as 两年后 or 第二次世界大战前. Is this grammatically correct? Or is it wrong but nonetheless used everywhere? (I know these phrases are often used but would like to know if it is correct.)

**Tags:** grammar
> **Comments:**
> **username_1**: look at examples in jukuu  
> **username_0**: @user6065 I checked it out and got many examples. I also noted it in *"(I know these phrases are often used but would like to know if it is correct.)"*.  
> **username_1**: 之 can be replaced by 以 if not omitted, grammar topic(外国人实用汉语语法）：方位词组（phrase of locality)表示时间：夜里，晚上， **三天前**  ，  **饭后** ，一个星期左右，一个月以前，(no mention of 之  only 以) 之 supplies official color  
> **username_1**: according to C. grammar 前，后，内，etc. are special types of nouns (方位词）, cf."实用现代汉语语法＂（一）。。。用于名词或名词短语后表示时间：三天前（后），十年后，三个月内，其中，本世纪中， （二）合成方位词１。合成方位词的构成。单纯方位词前边加上＂以＂或＂之＂或者（for position）后边加上＂边＂、＂面＂、＂头＂要读轻声。不同的方位词与＂以＂、＂边＂等组合的情况不完全相同。  
> **username_0**: @fefe Is 第二次世界战争 not a correct word? It was written as such in [my textbook](https://www.amazon.com/Modern-Mandarin-Chinese-Grammar-Practical/dp/0415827140/).  
> **username_2**: As a native, this is the first time that I see WWII written in Chinese as 第二次世界战争. I even tried a search in case it may be called this somewhere, but the result is not promising.  

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## 2 answers

### Answer by username_3 on 2017-08-30. Score: 2 | Accepted answer

...前 and ...内 are the short version of 之前 and 之内 respectively.

They are completely interchangeable, ...前==之前， ...内==之内.
三天前==三天之前，三天内==三天之内，第二次世界大战前==第二次世界大战之前

...后==之后 is the same thing. 两年后==两年之后

The only difference is longer ones look more formal.

> **Comments:**
> **username_0**: Thanks. So is the rhythm of a syllable also considered here? (e.g. if omitting 之 is better phonetically, it should be omitted, etc...)  
> **username_3**: ...前 is used more often than 之前, because it's concise. 之前 is a bit redundant. 之 was inherited from ancient Chinese like 其, so it's only used in certain fixed scenarios. But sometimes in a song or poem, in order to make each line aligned or for some kind of rhyme considerations, they might intentionally add 之. "十年", a Chinese song, they put “十年之前” for this kind of consideration.  
> **username_2**: If what before “前" has only one character, you usually will not use "之前". E.g., for 饭前, you usually will not say 饭之前, although I think people can understand.  
> **username_3**: @fefe Yeah, I'd been thinking about that case too. 饭之前 is a bit odd as people rarely say it. However, 晚饭之前 or 午饭之前 sounds natural. It's tricky, huh!  

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### Answer by username_4 on 2017-08-31. Score: 0

之 mostly means 的
~之前 = ~的前面
~之后 = ~的后面
~之内 = ~的里面

if ~ is time，
~之前 = before~
~之后 = after~
~之内 = in/among~

美国之音 = 美国的声音 = VOA（Voice of America）


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