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成人， せいじん
1. adult, grownup
2. becoming an adult, coming of age, growing up (to be a man, woman)
成人，成年
で
1. at, in
2. at, when
3. by, with
4. within, in
5. and then, so
6. and, then
7. let me tell you, don't you know
表示范围
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
