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夜更かし， 夜更し， 夜ふかし， よふかし
1. staying up late, keeping late hours, sitting up late at night, nighthawk
tbd
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いけない
1. bad, wrong, naughty
2. must not (do, be), should not, ought not to
3. useless, no good, bad
4. hopeless, beyond hope
5. unfortunate, a shame, a pity
6. unable to drink (alcohol)
7. so as not to ..., so that ... (won't), in case ..., for fear that ...
以免……，以免……，以防万一……，担心……，唯恐……；坏了！坏的，错的；无望，毫无希望；真不幸，真遗憾，真可惜
は
1. indicates sentence topic
2. indicates contrast with another option (stated or unstated)
3. adds emphasis
指示句子的主题；表示与另一选项（无论是否明确提及）形成对比；表示强调
