なくてはいけないHarus, Wajib

ねばならない and なくてはいけない express obligation or necessity, saying something 'must' or 'needs to' be done. They are equivalent in meaning, but ねばならない is a highly formal expression used primarily in the written language and in historical speech. Note that in colloquial, everyday conversation, なくてはいけない is often shortened to なくちゃ.

なくちゃ・なきゃ and なくてはいけない express obligation or necessity, saying that something 'must' or 'needs to' be done. なくてはいけない is more formal and often appears in writing or official contexts. In contrast, なくちゃ・なきゃ are casual contractions (of なくては and なければ) used in everyday speech with friends and family.

なくてはいけない and なくてはならない express obligation or necessity, meaning something 'must' or 'needs to' be done. They are equivalent in meaning, but ならない is slightly more formal and more common in written language, such as rules or regulations. In casual speech, both forms are often shortened to なくちゃ, with the いけない or ならない part left implied.

なくてはいけない and なければいけない express obligation or necessity, saying something 'must' or 'needs to' be done. They are equivalent in meaning, with the only difference being that the なければ version is slightly more formal, though the difference is not highly significant. Note that in casual speech, these forms are often shortened to なくちゃ and なきゃ, respectively.

なくてはいけない and なければいけない express obligation or necessity, saying something 'must' or 'needs to' be done. They are equivalent in meaning, but the なければならない version is slightly more formal, and thus more likely to be found in written rules, etc. Note that in casual speech, these forms are often shortened to なくちゃ and なきゃ, respectively.

なくてはいけない mengekspresikan keharusan atau kewajiban, yaitu sesuatu yang 'harus' dilakukan. Sebaliknya, てはいけない berarti sesuatu yang 'tidak boleh' atau 'tidak dapat' dilakukan. Bentuk ini bisa membingungkan bagi pelajar: なくてはいけない terlihat negatif tetapi artinya 'harus' (secara harfiah: 'tidak baik kalau tidak [dilakukan]'), sedangkan てはいけない terlihat positif tetapi artinya 'tidak boleh' (secara harfiah: 'tidak baik kalau dilakukan').

なくてはいけない expresses obligation or necessity, saying something 'must' or 'needs to' be done. なくてもいい has the opposite meaning, saying that one doesn't have to do something (literally, 'it's okay not to do'). For example, 食べなくてはいけない means '(You) must eat it', while 食べなくてもいい means '(You) don't have to eat it.'

ないと, なくちゃ, and なくてはいけない express obligation, meaning something 'must' or 'needs' to be done. なくてはいけない is more formal, while ないと (the negative form plus conditional と) is a casual alternative. While いけない can be replaced with ならない, ないと is usually used on it's own or followed by いけない or だめ, the more casual option.