This means 'if you do X, then something bad will happen'. It shows a bad result will come from an action.
Verb [て-form] + はPrimary
い-Adjective [て-form] + は
な-Adjective [+ で] + は
Noun [+ で] + は
This means 'if you do X, then something bad will happen'. It shows a bad result will come from an action.
そんな無茶な運転をしては、いつか大事故を起こすぞ。
If you keep driving recklessly like that, you're going to cause a major accident one day.
子供の頃、少しでも嘘をついては、母にひどく叱られたものだ。
When I was a child, if I told even a small lie, I would get severely scolded by my mother.
準備運動をしないで急に運動しては、怪我をするもとだ。
If you suddenly exercise without warming up, you're just asking for an injury.
これしきの失敗で諦めては、大きな成功は望めません。
If you give up over a trivial failure like this, you cannot hope for great success.
FormalNon PastAffirmativeMid SentenceHypotheticalWork & CareerBusiness & FinanceEmotions & Psychology
彼は書いては消し、書いては消しを繰り返していて、一向に筆が進まない。
He keeps writing and erasing, writing and erasing, and is making no progress whatsoever.
This grammar is like a red warning light. It tells you that if you do something, a bad thing will happen. It shows a problem or something you will regret.
This is different from "~tara" or "~to". Those just mean "if" or "when". "~te wa" means something bad will happen. It is not as strong as "~you mono nara". That is for very bad, unlikely things. "~te wa" is for normal warnings.
Don't use this when you are speaking casually. For example, saying "そんなことをしてはダメ" sounds too formal. You can shorten it to "そんなことしちゃダメ" instead.
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