逍遥游 发表于 2017-7-11 23:16 Sx=400×20×（1200/2-20/2）+12×[（1200-20×2）/2]×[（1200-20×2）/2/2] =400×20×590+12×580×290 ...
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手机版|小黑屋|第一证书
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