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ただいま， 只今， ただ今， 唯今
1. I'm home!, I'm back!, it's me!
2. now, at present, at the moment
3. just now, a moment ago
4. at once, right away, in a minute, shortly, soon
我回来了；是我；现在；刚才；马上
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
