べきではないTidak seharusnya, Tidak boleh, Semestinya tidak

Kedua ungkapan ini memiliki makna yang berlawanan: なければいけない berarti 'harus', sedangkan べきではない berarti 'sebaiknya tidak'. なければいけない menunjukkan keharusan atau aturan, sementara べきではない lebih bernuansa nasihat moral atau sosial, misalnya 行かなければいけない ("Kamu harus pergi") dan 行くべきではない ("Kamu sebaiknya tidak pergi").

なくちゃ and なきゃ are casual ways to express obligation, similar to 'I need to…' or 'I have to…' in English. In contrast, べきではない has the opposite meaning—'should not' or 'ought not'—and is more formal. It conveys a sense of societal expectation or what is considered proper, rather than reflecting the speaker's immediate or personal needs.

はずだ digunakan untuk menyatakan asumsi atau harapan berdasarkan alasan atau konteks, misalnya 雨が降るはずだ ("Seharusnya akan hujan"). Sebaliknya, べきではない menyatakan kewajiban moral atau sosial yang kuat untuk tidak melakukan sesuatu, misalnya 嘘をつくべきではない ("Kamu tidak seharusnya berbohong").

たほうがいい is used to give advice or make a suggestion, often expressing the speaker's subjective opinion on what they believe would be better. It's commonly used in everyday conversation. In contrast, べきではない has the opposite meaning and is more formal. It conveys an expectation or rule about what 'should not' be done, rather than a personal opinion.

Kedua ungkapan ini berlawanan: なければならない berarti 'harus', sedangkan べきではない berarti 'tidak seharusnya'. なければならない menunjukkan keharusan atau aturan, sementara べきではない lebih bernuansa nasihat moral atau sosial. Misalnya, 行かなければならない ("Kamu harus pergi") dibandingkan dengan 行くべきではない ("Kamu tidak seharusnya pergi").

ことだ suggests what one should do as advice or a general guideline, e.g. 無理をしないことだ ('You should take it easy.') べきではない expresses the opposite, indicating what one should not do based on moral or social expectations, e.g. 人を見た目で判断すべきではない ('You shouldn't judge people by appearances.')

ものだ expresses general or societal expectations, e.g. 子どもは早く寝るものだ ('Children are supposed to go to bed early.') べきではない carries the opposite nuance, conveying that one should not do something based on moral or social reasoning, e.g. 人を見た目で判断すべきではない ('You shouldn't judge people by appearances.')

べき expresses strong obligation or moral judgment, as in doing something because it is right or proper, e.g. 約束は守るべきだ ('You should keep your promises.') べきではない is the negative form, used to advise against actions considered wrong or inappropriate, e.g. 人を見た目で判断すべきではない ('You shouldn't judge people by appearances.')

てはいけない expresses prohibition, meaning something 'must not' or 'cannot' be done. In contrast, べきではない suggests that something 'should not' be done, often implying it's improper or that there's a better option. While both express negative recommendations, てはいけない is more authoritative and used for rules, whereas べきではない carries a more subjective nuance.

ないほうがいい is used to advise or suggest not doing something, similar to 'You shouldn't…' It is a common expression that reflects the speaker's personal or subjective opinion. べきではない can carry a similar meaning but is more formal, with a nuance of stating what one 'ought not to' or 'should not' do based on social norms or what is considered proper, rather than personal advice.