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       I had four small children, their father died in an unknown disease. Money was always 1，but we had a roof over our heads，2on the table, clothes onour backs and, if not a lot, always enough.

        It was 3time and the big excitement for the kids was the 4of Christmas shopping at the mall.They talked and planned for weeks5time, asking each other andtheir grandparents 6they wanted for Christmas.I had saved $120 for presents to be shared by all five of us.

       The big day arrived and we started 7early. I gave 8of the four kids a twenty­-dollar bill and 9them tolook for gifts that cost about four dollars each.Then everyone 10．We had two hours to shop.

       Back in the car driving home, everyonewas in high Christmas spirits, laughing and teasing each other with hints and11about what they had bought. My younger daughter, Ginger, who was about eight years old, was 12quiet.I noted she had 13onesmall, flat bag with her. I could see enough 14the plastic bag to 15thatshe had bought candy bars—fifty-cent candy bars！Iwas so angry.What did you 16that twenty­-dollar bill I gave you？I wanted to17at her, but I didn't say anything 18we got home.I called her into my bedroom and closed the door, ready to be angry again when I asked her what she had done with the money.This is what she told me：

“I was looking 19，thinking of what to buy, and I stopped to read the little cards on one of the Salvation Army's‘Giving Trees.’One ofthe cards was for a little girl, four years old, and all she wanted for Christmas was a doll with clothes and a hair brush.20I took the card off the tree and bought the doll and the hairbrush for her and took it to the Salvation Army booth.”

小明有9根a厘米长的小棒和6根6厘米长的小棒，(n与6不相等，且均不为0，他用其中的12根搭成一个长方体框架，长方体框架的棱长和是____厘米。(接头处的长度忽略不计)