题目内容：
提示：百货公司的Jackson先生打电话找Brown先生，告诉他他订的商品有了。秘书告诉Brown先生接电话。Brown先生得知后向Jackson先生表示感谢。Jackson: Hello ! ( 51 ) your manager, Mr. Brown?
Secretary:（52）, please. Mr. Brown, You are wanted on the phone.
Brown: Hello, （53）?
Jackson: This is Jackson. ( 54 ) speaking?
Brown:（55）.
Jackson: I'm from the department store. Your order is ready.
Brown: Thank you a lot. I'll go and get it tomorrow.
阅读对话，回答题。
请在51处填写正确答案
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