It"s a nice day,isn"t it? Yes,isn"t什么意思

反意疑问句。
今天天气真好，不是吗？
不（用肯定词做否定回答），天气不好。

真是美好的一天，不是吗？
（反义疑问句，反问自己前面说的话，加强语气）

这是美好的一天，难道不是吗？是的，这是美好的一天。

它“是个好天，并非”吨呢？
是的，并非“吨

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