屋顶的两面斜面都有破瓦片.On both slopes of the roof there are broken tiles.伽利略让小金属球从斜面滚下.Galileo rolled small metal balls down the incline.图3.21画出了平行于斜面的、相互保持平衡的几个力.Figure 3.21 shows the forces parallel to the plane that are respons...
用脑力激荡法穷举系统中主要参与者的使用者目标 ( 参与者 — 目标清单 ).Brainstorm and list the primary actors'goals against the system ( actor - goal list ).用脑力激?法穷举可能的失败条件与替代路径成功条件.Brainstorm and list possible failure conditions and alternate succ...