光滑水平桌面上有A、B两个物块，B的质量是A的n倍．将一轻弹簧置于A、B之间，用外力缓慢压A、B．撤去外力后，A、B开始运动，A和B的动量大小的比值为（   ）

一张宽为6cm的平行四边形纸带ABCD如图1所示，AB=10cm，小明用这张纸带将底面周长为10cm直三棱柱纸盒的侧面进行包贴（要求包贴时没有重叠部分）．小明通过操作后发现此类包贴问题可将直三棱柱的侧面展开进行分析．

阅读短文，回答问题

One afternoon, Mrs. Green’s husband wanted to catch the 3: 30 flight to London to have an important meeting. She was very surprised when he telephoned her at     5 o’clock and said that he was still at the airport.

“What happened to you? ” asked Mrs. Green.

“Well, ” said Mr. Green, “Everything was going fine. I got my ticket, checked my bag and waited in line. I walked across the runway(跑道) to the airplane and I saw my friend Jack Scott, who was an airplane engineer. I shouted to him and a policeman caught me. ”

“Why did he catch you? ”

“I don’t know, ” said Mr. Green, “As soon as he heard my shout, he ran towards me and caught me. ”

“What did you shout to your friend? ”

“All I said was ‘Hi，Jack’. You know that’s the usual way we say hello to our friends. ”

“But you don’t know the sentence ‘Hi, Jack’ also means to take control(控制) of a plane by force(武力). ”