如图，△ABC中，A，B两个顶点在x轴的上方，点C的坐标是（﹣1，0），以点C为位似中心，在x轴的下方作△ABC的位似图形△A′B′C，并把△ABC的边长放大到原来的2倍．设点的对应点B′的横坐标是2，则点B的横坐标是____ ．

一个人意外摔倒，体表未见大量出血，但心跳和呼吸都骤然停止。他受损伤的部位可能是

下列结论正确的是（　　）
①函数关系是一种确定性关系；②相关关系是一种非确定性关系；③回归分析是对具有函数关系的两个变量进行统计分析的一种方法；④回归分析是对具有相关关系的两个变量进行统计分析的一种常用方法．

根据对话内容，从方框内的选项中选出能填入空白处的最佳选项，选项中有两项为多余选项。
Mrs. Lee: Hello. 68178502.
David:  Hello.____  ?
Mrs. Lee: Sorry.____ . Can I take a message?
David:  Yes. This is David, Bruce’s friend. I want to ask him for some Chinese ancient coins. He told me he had got some recently. ____  . I don’t care if they were made of different metals. I just want to add some more coins in my collection.
Mrs. Lee: OK. I’ll tell him. Would you like him to ring you back later?
David:  Well, I won’t be at home later this day. Would you please ask him to ring me tomorrow morning?
Mrs. Lee: Sure.____ ?
David:   Oh, sorry.____   The new number is 66129853.
Mrs. Lee: OK. I’ll write a message for him.
David:   It’s really nice of you, Madam. Thank you very much. Goodbye!
Mrs. Lee:  Bye!