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体力， たいりょく
1. physical strength, power, stamina, endurance, vigor, resistance to disease
2. strength (of a business, economy, etc.)
tbd
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衰える， おとろえる
1. to become weak, to decline, to wear, to abate, to decay, to wither, to waste away
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
