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鈍る， にぶる， なまる
1. to become blunt, to grow dull
2. to become less capable, to weaken, to falter
tbd
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
