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　　　　These particles are very similar to だけ, but they're syntactically different. 

しか must be used with the negative form of a verb. It may follow nouns and even other particles such as those with に, で, and まで. In translation, it is close to "just/only" but with a nuance of "there is no choice but to," especially after verbal phrases.

Particle Note: The particle に may be deleted before しか!  

1. 後あとたった（の）一週間いっしゅうかんしかありません。
    There's only one week left.

2. セミナーのレポートの締(し)め切(き)りは明日(あした)だ。徹夜(てつや)するしかない。
The deadline for the seminar report is tomorrow. I have no choice but to work on it all night long.

3. 今日のおやつこれしかないの。(Casual)
    Is this all there is for snacks today?

4. （事前じぜんに・あらかじめ）伝つたえるしかない。
     I have no choice but to tell.

5. 歩くしかありません。
    You have no choice but to just walk.

6a. ローマ字だけ書けます。                  I can only write Roman letters.
6b. ローマ字しか書けません。              I can't write anything but Roman letters.

Particle Note: Although だけを is possible and relatively common, the equivalent with しか, をしか, is very literary and doesn't show up often.

7. 私が目に見える美をしか信じなかった以上、この態度は当然である。
    Since I could only believe the beauty that I could see in my eyes, this attitude is natural. 
From 金閣寺 by 三島由紀夫. 

8. いつしか時が流れた。
      Time slid by. 

Set Phrase Note: いつしか ＝ いつの間にか知らないうちに. It doesn't need to be used to be with the negative. 

You may also use だけ and しか together creating だけしか. Also, しか may be seen as しきゃ and っきゃ in slang.

9. やるっきゃないな。
     I have no choice but to do it.

 ほか Continued

    ほか means "aside from." Technically, it can also be seen in ～ほかない, which is synonymous to ～しかない.

10. 社長しゃちょうほか五名ごめいが出席しゅっせき
        Five in attendance aside from the company president.

11. どこかほかを探さがす。
      To search the rest.

12. 彼はこのほかに何なんと言った？
    What else did he say?

13a. 弁護士べんごしは文書ぶんしょだけでなく、口頭こうとうでも説明せつめいしてくれた。
13b. 弁護士は文書をもってするほか、口頭でも説明してくれた。
        The lawyer explained orally aside from the use of documents.