〜てはいけません

## What it means This means "you must not ~" or "you're not allowed to ~." It's used to tell someone that something is forbidden.

## When to use it Attach ては to the **te-form** of a verb, then add いけません. Because it sounds firm, you'll hear it in rules, signs, and warnings — from parents, teachers, or notices in public places. In casual speech, people often shorten it to just ちゃだめ.

## Don't confuse it with This is the flip side of てもいいですか, which asks for permission. If the answer to "May I ~?" is no, てはいけません is the pattern used to state the rule. Don't mix up ては with ても — swapping just one letter turns "must not" into "may."