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警戒， けいかい
1. vigilance, caution, alertness, precaution, being on guard
警戒
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警備， けいび
1. defense, defence, guard, policing, security
警备
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
