〜てはいけない Must not / Is forbidden
Core meaning - Must not / Is forbidden
Form - Verb て-form + はいけない; Verb て-form → ちゃいけない; Verb て-form → ちゃだめ
Usage - Focus on the highlighted segment in each example; surrounding words can change while the pattern function stays the same.
Use this pattern for its grammatical function, not as a literal word-by-word translation.
See examples below for varied real-world usage.
てはいけない = must not, prohibited
- ここで食べてはいけない
Casual forms
- てはいけない → ちゃいけない → ちゃだめ
vs なくてはいけない (must do)
You must not take photos here.
You cannot eat that!
You must not be late.
You must not tell lies.
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