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兄弟， きょうだい， けいてい
1. siblings, brothers and sisters
2. brothers
3. siblings-in-law, brothers-in-law, sisters-in-law
4. mate, friend
手足，兄弟姐妹
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
