Rename folders + misc fixes

🔰 Grammar/Must (not).md

@@ -0,0 +1,98 @@
+# Must & must Not
+
+## が必要・必要がある
+
+Means "needed" or "necessary".
+が{必要|ひつよう} is used mainly with nouns (can be used with verbs by appending こと before).
+{必要|ひつよう}がある is used with verbs.
+
+> [!info] Example
+> {今時|いまどき}、{携帯電話|けいたいでんわ}==が必要です==。
+> Nowadays, a cell phone is necessary.
+> 
+> 今日はパン{屋|や}に行く==必要がない==。
+> No need to go to the bakery today.
+
+## Must
+
+### なくちゃ・なきゃ
+
+Only used on casual spoken conversations.
+This form is used with the negative form of a verb (ない), and adding なくちゃ and optionally one of the following ending: だめ, いけない, いけません, ならない, なりません.
+
+なくちゃ is the shortened form of なくては.
+なきゃ is the shortened form of なければ.
+
+> [!info] Example
+> {歯|は}を{磨|みが}か==なくちゃいけない==。
+> I must brush my teeth.
+
+### なくては「いけない・ならない」
+
+Also formed with the negative form of a verb.
+
+> [!info] Example
+> 今{遅|おそ}いね。{寝|ね}に行か==なくてはいけない==。
+> It's late now. I have to go to sleep.
+
+### なければ「いけない・ならない」
+
+Also formed with the negative form of a verb.
+
+> [!info] Example
+> {事務所|じむしょ}では{静|しず}かにし==なければならない==。
+> You have to be quiet in the office.
+
+### ないといけない
+
+Also formed with the negative form of a verb.
+In casual contexts, can be shortened as ないと.
+
+> [!info] Example
+> 今日は{勉強|べんきょう}し==ないといけない==。
+> I have to study today.
+
+### Comparing いけない and ならない
+
+* ==いけない== is the standardly used form. It implies a subjective view, that it would be better to do something, to avoid negative consequences (eg: brushing one's teeth, eating well, etc).
+* ==ならない== is usually more formal or in written form. It implies a is more objective view, something that has to be done because there's no other way (eg: respecting the law, paying taxes, etc).
+
+### Comparing なくては, なければ and ないと
+
+なくては and なければ are generally interchangeable in speech. However:
+* ==なくては== is generally used when there is _no penalty_ for not complying.
+* ==なければ== is generally used when there _is a penalty_ for not complying.
+* ==ないと== is lighter and does not imply that there can or cannot be penalty. Its construction is based on the [[Conditional#と]] particle, and should be based on knowledge or experience.
+
+## Must not
+
+#### 「ちゃ・じゃ」「だめ・いけない・いけません」
+
+Only used on casual spoken conversations. いけません is a bit more formal.
+This form is used with a V-て, depending on the ending:
+* with て, ちゃ is used.
+* with で, じゃ is used.
+
+> [!info] Examples
+> その{花|はな}を食べ==ちゃだめ==。
+> Don't eat those flowers.
+> 
+> {花瓶|か|びん}の水を{飲|の}ん==じゃいけない==。
+> Don't drink the water of the flower vase.
+
+### てはいけない
+
+Used in a more formal or written manner. Used with a V-て.
+
+> [!info] Example
+> {鉄道|てつ|どう}に{歩|ある}い==てはいけません==。
+> Do not walk on the railroad.
+
+### なくてもいい
+
+Means "don't have to". Used with a verb in the negative form (ない), appending なくてもいい.
+Can also be used as なくていい.
+
+> [!info] Example
+> 今日はレストランで{手伝|て|つ}わ==なくてもいい==。
+> You don't have to help out at the restaurant today (it's okay if you don't help at the restaurant today).