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素材， そざい
1. ingredient, (raw) material, resource
2. unprocessed timber, raw timber
3. subject matter, topic
原料、原材料
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
