http://www.mysanco.com/index.php?class=wenku&action=wenku_item&id=35 Jerusalem Chords Bridge 耶路撒冷弦桥 梯子包络线竟然是抛物线？
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三月 15th, 2013 at 15:28
http://www.mysanco.com/index.php?class=wenku&action=wenku_item&id=35
Jerusalem Chords Bridge
耶路撒冷弦桥
梯子包络线竟然是抛物线？