that'll be the day

短语
中文释义
英 /ˌðætl̩ biː ðə ˈdeɪ/    美 /ˌðætl̩ bi ðə ˈdeɪ/

英文释义

短语
  1. Said in reply to something that one believes will never happen. New-Zealand,idiomatic,informal
    — I’m going to get into work on time today. — That’ll be the day!

词源

Originally referring to a significant day in the future regarded as worth waiting for.
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