못하면

못하면

"못하면" means "if unable" or "if one cannot."

In this usage, '못하면' directly relates to the inability to perform the specific action of keeping an appointment, combined with a practical advice.

약속을 못하면 미리 알려 주세요.

Please inform me in advance if you can't keep the appointment.

In this sentence, '못하면' conveys the conditional meaning 'if you cannot do (something)', indicating a hypothetical situation.

못하면 배우는 게 필수적입니다.

If you can't do it, learning it is essential.

Here '못하면' again represents the conditional 'if you cannot do,' suggesting an alternate approach when encountering difficulty.

너무 어려운 일을 못하면 쉬운 것부터 시작하세요.

If you can't do very difficult tasks, start with the easy ones.