I am a beginner in Japanese so I was trying to write some simple sentences to
practice my vocabulary and grammar.

I wanted to write the sentence:

> My friend is in Japan for three weeks.

as:

> 私の友達が 三週間 日本に います。

I am unsure if I should put any particle after 三週間 and whether this sentence
is grammatically correct at all.
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2016-08-17T16:43:13.330
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2019-04-23T07:02:50.630
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question
grammar particles syntax
Particles after time expressions like "三週間"
[[間]{かん}](http://jisho.org/search/%E9%96%93) itself is functioning as a suffix
indicating 'interval' or 'period of time'. In other words, '三週間' literally
translates to '三週 (three weeks) + 間 (during or for)'. Therefore, you don't
need any other particle or suffix after '三週間'.

One more important thing you should note is [Japanese normally doesn’t put
spaces between words](http://www.japanesereview.com/things-that-make-japanese-
hard/).
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2016-08-17T17:04:51.793
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2016-08-18T07:11:39.943
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answer
You could insert:

```

       私の友達が三週間のあいだ日本にいます。
    
       私の友達は、三週間の間 日本にいます。
    
```

三週間の間 sounds redundant but it's correct.

Many people insert に making it "...週間の間に" but it's often incorrect (sloppy
diction).

This first example (below) is ungrammatical / illogical -- or especially
sloppy.

> 【衝撃】たった4週間の間に毎日3Lの水を飲み続けた女性の変化がヤバすぎ！ 皆さん、普段の生活の中で意識して”水”を飲 ... .......
```

          ( I suppose she got prettier and/or younger-looking. )
    
```

> 緊急警告！！一週間の間に「東京大地震」がくる可能性があります。
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2016-08-18T22:30:13.667
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answer