将下列句子排成一段完整的对话。
（1）No, it isn't.Perhaps it's Yang Ling's.
（2）Helen, What's that over there?
（3）It's a key.
（4）Hi, Yang Ling.Is this your key?
（5）Is that your key?
（6）Oh, yes.Thank you very much.
（7）Not at all.
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