(·黑龙江省哈三中高三上月月考) 30. ---Where did you meet him? ---It was in the hotel _________ I was staying. A. that B. how C. where D. which 答案:C已知函数的图象过坐标原点O,且在点(-1,f(-1))处的切线的斜率是-5.(Ⅰ)求实数b,c的值; (Ⅱ)求f(x)在区间[-1,2]上的最大值;(Ⅲ)对任意给定的正实数a,曲线y=f(x)上是否存在两点P、Q,使得△POQ是以O为直角顶点的直角三角形,且此三角形斜边中点在y轴上?说明理由.